- NEW: Arab League calls on opposition to form national unity government
- NEW: At least 111 die across Syria on Sunday, opposition says
- Reporter says a Damascus hospital apparently was attacked by rebels
- Rebels say they have seized a border gate between Syria and Turkey
(CNN) -- The Arab League will offer Syrian President Bashar al-Assad "a safe exit" if he steps down quickly and leaves the country, a senior Arab League official said late Sunday after the group held an emergency meeting in Qatar.
The official provided no further details because he is not authorized to speak to the media.
Qatari Foreign Minister Sheikh Hamad bin Khalifa Al-Thani did not discuss an exit plan when speaking with reporters after the five-hour meeting, but confirmed "there is an agreement on the need for the swift resignation" of Assad.
"We call on the opposition and the Free Syrian Army to form a government of national unity," Sheikh Hamad said.
Meanwhile, conflict continued in Syria, with the cities of Aleppo and Damascus bearing the brunt of Sunday's violence.
In a video posted online Sunday, the head of the rebel Free Syrian Army in Aleppo announced an operation "to liberate the city of Aleppo from the rule of the Assad thugs, whose hands were blood-stained by heinous crimes against our people."
Brig. Gen. Abdel Jabbar Al-Obeidi urged regime soldiers to defect or step aside and not fight against his men, with the promise that no one would be harmed.
On Sunday, July 22, a Syrian refugee looks out from a bus as he arrives at a refugee camp in Turkey, which is opposite of the Syrian commercial crossing point Bab al-Hawa. 
Syrian refugees flee from a refugee camp nicknamed "Container City" on the Turkish-Syrian border in Kilis province, southern Turkey, on Sunday. 
Smoke from artillery shelling rises above Jbatha Al-khashab. 
An armed Syrian rebel wearing the jersey of FC Barcelona rests with comrades near the northern city of Aleppo on Sunday. The rebel Free Syrian Army announced the start of the battle to "liberate" Aleppo, Syria's commercial hub and a traditional bastion of President Bashar al-Assad's regime. 
In this photo released by the Shaam News Network, a truck burns after shelling in the Erbeen suburb of Damascus on Saturday, July 21. 
Refugees fleeing the violence in Syria arrive by bus in Baghdad, Iraq, on Saturday. 
Turkish soldiers stand guard at the Cilvegozu border gate in Reyhanly that connects to Syria's Bab al-Hawa post. An estimated 120,000 people have fled Syria to Turkey, Iraq, Lebanon and Jordan. 
Burned-out trucks at the Bab al-Hawa Syrian border post with Turkey on Friday, July 20. Syrian rebels seized control of the post after a fierce battle with Syrian troops, an AFP photographer at the scene reported. 
Syrian soldiers celebrate in the al-Midan area in Damascus on Friday. Syrian regime forces routed rebel fighters from the Damascus neighbourhood of Midan, Syrian state television reported, saying troops had "cleaned" the district of "terrorists." 
Journalists are shown a dead body on a government tour of the al-Midan area in Damascus on Friday. 
Members of Syria security forces rest in the al-Midan area in Damascus on Friday. 
Syrian army soldiers hang their national flag in a partially destroyed neighborhood in the al-Midan area in Damascus. 
Smoke hangs in the air in a partially destroyed neighborhood in the al-Midan area in Damascus. 
Members of Syria security forces pose for photographers in the al-Midan area in Damascus after driving out the rebel fighters. 
Syrian residents take goods from a truck that rebels captured at the Bab al-Hawa border crossing with Turkey on Friday. 
A picture released by the official Syrian Arab News Agency on July 19 shows Syrian General Fahd al-Freij meeting with President Bashar al-Assad in Damascus after his swearing-in ceremony as defense minister. 
A man holds up a picture of President Bashar al-Assad at a former police station in Atareb after clashes between Syrian soldiers and Free Syrain Army near Aleppo on Thursday, July 19. Rebels seized control of border crossings with Iraq on Thursday, dealing a new blow to al-Assad, as China and Russia dismayed the West by blocking U.N. action against his regime. 
People walk along the street in Atareb amidst damage caused by clashed between Syrian soldiers and the Free Syrian Army. 
A Syrian man checks the former police station of Syrian regime after a clash at Atareb on Thursday. 
Smoke ascends from from alleged shelling of the Syrian village of Jebata al-Khashab as seen from the hill village of Buqaata in the Israeli-annexed Golan Heights on Thursday. 
The death toll in Syria on July 12 reached 287, making it the bloodiest day in Syria since the uprising began. As it has done consistently, Syrian state television blamed "armed terrorist groups" for the killings. 
A Syrian woman sits with her grandson outside a damaged building after attacks in the Syrian village of Treimsa on July 13, 2012. More than 200 people were massacred in the town, according to activists. 
A Syrian demonstrator holds an opposition flag during a protest in Damascus on July 2, 2012. There have been increasing reports of violence in the Syrian capital. 
Syria's President Bashar al-Assad waves as he arrives for a speech to Syria's parliament in Damascus on June 3, 2012. The embattled president denied that government forces were behind the "outrageous" massacre in Houla. 
People gather at a mass burial on May 26, 2012 for victims reportedly killed during an artillery barrage from Syrian forces in Houla. The attack left at least 108 people dead, including nearly 50 children, according to the United Nations. 
Members of the Free Syrian Army return to Qusayr on May 12, 2012 after an attack on Syrian regime forces in the village of Nizareer, near the Lebanese border in Homs. 
A U.N. observer speaks with Syrian rebels and civilians in the village of Azzara on May 4, 2012, days before the country's parlianemtary polls were held against a backdrop of unrest. 
Thousands of Syrians wave their national flag and hold portraits of President Bashar al-Assad and Lebanon's Hezbollah chief Hassan Nasrallah, right, during a rally to show support for their leader on March 29, 2012 in Damascus. 
Syrian rebel fighters man a checkpoint leading into the town of Taftanaz in the rebel stronghold province of Idlib on March 20, 2012. 
A Free Syrian Army rebel mounts his steed in the Al-Shatouria village near the Turkish border in northwestern Syria on March 16, 2012, a year after the uprising began. The Free Syrian Army is an armed opposition group made up largely of military defectors. 
Syrian refugees walk across a field before crossing into Turkey on March 14, 2012. International mediator Kofi Annan called for an immediate halt to the killing of civilians in Syria as he arrived in Turkey for talks on the crisis. 
A day after the twin suicide bombings, Syrian mourners pray over the coffins of the 44 people killed during a mass funeral in Damascus. 
A Syrian man who was wounded in a suicide attack rests at a hospital in Damascus on December 23, 2011. Suicide bombers hit two security service bases in the Syrian capital, killing dozens of people. 
Arab foreign ministers attend an emergency meeting at the Arab League headquarters in Cairo on October 16, 2011, to discuss the crisis in Syria. 
U.S. Secretary of State Hillary Clinton speaks to the media in Washington on August 18, 2011. Clinton said U.S. sanctions on Syrian oil "strike at the heart of the Syrian regime." 
Syrian youths wave national flags while army troops drive out of Daraa on May 5, 2011. During a week-long military lockdown of the town, dozens of people were reportedly killed in what activists described as "indiscriminate" shelling on the city. 
Syrians in Damascus protest in the street on March 25, 2011, after clashes with government forces in Daraa left several dead. 
Supporters of Syrian President Bashar al-Assad rally on April 1 in Istanbul, Turkey, as delegates from dozens of countries gather to push for ways to end the deadly violence in Syria. The United Nations estimates more than 10,000 people have been killed since the beginning of the crisis in March 2011. The conflict is now being labeled a civil war by the International Committee of the Red Cross. 
Showdown in Syria Late Sunday, Syrian state television broadcast an "important" statement from the Information Ministry saying Western intelligence and "some Arab parties" are planning to hijack Syrian TV frequencies and deliver false news reports of a coup, defections, or cities having fallen into rebel hands.
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Attack a major blow to Syrian regime State TV said the stations "might use Syrian journalists under pressure after being kidnapped."
Ban: Syrian regime 'failed to protect civilians'
Fierce clashes erupted Sunday between regime and rebel forces in Aleppo, the commercial hub of Syria, opposition activists said.
"An entire building collapsed in Seif al-Dawla neighborhood after a regime tank ... targeted it with four shells," the Local Coordination Committees of Syria (LCC) said.
Syrian state-run TV cited an official media source as denying reports about Aleppo.
"Some terrorists are mobilizing their armed groups in the city in a similar attempt to distort the reality and the facts on the ground just like they tried to do in Damascus," the network said.
"Our heroic armed forces and the special authorities in Aleppo ... have been tracking down the remnants of the terrorists, killing a large number of them." Others surrendered, while still more fled toward Turkey, according to the report.
By the end of the day Sunday, 111 people had died across Syria, including 56 people in and around Damascus and three in Aleppo, the LCC said.
If rebels eventually gain control of Aleppo, it would mark a pivotal point in the Syrian crisis and deal a heavy blow to al-Assad's financial ties.
Separately, rebels said Sunday they had seized a border gate between Syria and Turkey at Bab al Salam.
"There were attempts to take over the border crossing of Bab al Salam for the last three days," Malik Kurdi, deputy commander of the Free Syrian Army, told CNN. "Yesterday, very late at night, FSA seized the gate completely, and now Syrian helicopters are flying around."
He said there are concerns Syrian forces could attack the gate.
Another FSA fighter, identifying himself as Abu Shawki, said the rebels gained control of all of Bab al Salam following fierce clashes in which many died. He said regime forces abandoned some of their tanks.
Aleppo and the capital city of Damascus have been al-Assad strongholds, but heavy clashes in Damascus over the past week, along with a recent bombing that killed four members of al-Assad's inner circle and government, suggest cracks in the regime's armor.
A mosque in Damascus came under attack Sunday from rocket and helicopter shelling while worshippers were inside, the LCC said. The mosque caught fire and "many" were killed, the group said.
But the Syrian regime denied reports of helicopter attacks in Damascus, saying it was "life as usual" in most of the city, Syrian state-run TV reported Sunday.
CNN cannot independently confirm reports of violence because the government restricts access by foreign journalists.
Alex Thomson, a correspondent with CNN affiliate ITN, wrote Sunday on Twitter that a military hospital in Damascus came under heavy fire, and a sustained firefight took place as rebels apparently attacked the building for about 90 minutes. The bodies of soldiers were at the hospital, he said; their funerals were canceled because of the hospital attack.
Thomson noted in a blog post he could not say for sure that rebels attacked the hospital, but soldiers at the hospital insisted it was under attack.
Separately, another opposition group reported that a senior scientist and expert in Syria's missile program was killed, along with his wife and son.
Retired Maj. Gen. Nabil Zugheib was assassinated in the Bab Touma district of Damascus, the Syrian Observatory for Human Rights said. There was no immediate claim of responsibility.
Thousands of Syrians race to borders
Damascus is largely isolated by checkpoints and tanks, witnesses said Saturday. Opposition groups say medicine is running out and residents are appealing for help.
The crisis started in March 2011, when a fierce government crackdown against protesters morphed into a nationwide uprising against the regime.
Video: How does Assad survive in Syria?
The United Nations estimates more than 10,000 people have been killed since the crisis began more than 16 months ago. But Rupert Colville, a spokesman for the office of the U.N. high commissioner for human rights, said the United Nations has not been giving out overall death toll numbers since December "because it became impossible to verify the numbers in any meaningful way."
Opposition groups tracking deaths have issued higher tolls. The LCC, for example, estimates more than 16,000 people, mostly civilians, have died.
The Syrian regime has taken a hit with military defections. An official from the Turkish Foreign Ministry said three brigadier generals from Syria arrived in Turkey last week and about two dozen Syrian generals have fled to Turkey.
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CNN's Mohamed Fadel Fahmy, Yousuf Basil, Holly Yan, Saad Abedine, Roba Alhenawi, Ivan Watson, Raja Razek, Yesim Comert and journalist Shiyar Sayed Mohamad contributed to this report.
