- Opposition activist: Tanks continue pummeling a neighborhood in Homs
- Syria's foreign minister will meet with his Russian counterpart in Moscow on Tuesday
- Special envoy Kofi Annan is expected to visit Syrian refugee camps in Turkey on Tuesday
- 143 people are killed in Syria on Monday, an opposition group says
Are you there? Send us your images or video. Also, read this report in Arabic.
(CNN) -- A deadline for Syrian troops to withdraw from cities came and went Tuesday morning, with no reports of change in the year-long crisis that has killed thousands.
An opposition activist in the besieged city of Homs said fresh shelling rained on two neighborhoods late Tuesday morning.
"Tanks hitting those areas remain in al-Qusoor neighborhood. So there is not a tank that pulled out from there," said the activist, identified only as Omar for safety reasons. "The humanitarian situation is worsening by the day. I went out to get food yesterday and could not find any store open in our area."
Hours before the deadline, reports of mounting carnage left world leaders doubtful of the regime's promises.
"Should the Syrian government yet again refuse to implement its commitments, make promises and then break them and continue and escalate the killing, then I think it will be clear to all that there isn't yet prospect for diplomatic solution," Susan Rice, U.S. ambassador to the United Nations, said Monday. "We still hope that that's possible, we still want to give that a final chance, but I don't think we, or anybody else, are particularly optimistic."
Early last week, diplomatic officials said the Syrian government agreed to an April 10 deadline to withdraw troops from cities. The agreement came after Syria said it accepted a peace plan laid out by U.N.-Arab League special envoy Kofi Annan.
But on Monday, the violence seemed to only intensify -- even spilling over into into Turkey and Lebanon.
Al-Assad's broken peace promise 
Russia, Syria prepare for talks 
Syria: Pullback 'requires guarantees' 
Expert: No cease-fire in sight in Syria At least 143 people were killed in Syria on Monday, according to the Local Coordination Committees of Syria, a network of opposition activists. That number was more than twice the death toll from Sunday.
And a Turkish official said three people at a refugee camp were shot by gunfire coming from Syria.
While the world waits to see what the regime will do Tuesday, Syrian Foreign Minister Walid al-Moualem will meet with his Russian Foreign Minister Sergey Lavrov in Moscow on Tuesday.
Russia, along with China, has repeatedly quashed attempts by fellow U.N. Security Council members to pass resolutions condemning the Syrian regime.
A possible stalemate on a cease-fire
Two days before the deadline, Syria denied it had ever agreed to a unilateral pullout.
Foreign Ministry spokesman Jihad Makdissi said notions that Syria had agreed to withdraw its troops from cities on Tuesday were "a wrong interpretation," the state-run Syrian Arab News Agency reported.
The regime will not commit to pulling out forces only to have "armed terrorist groups" attack, Makdissi said, complaining that Annan "has not offered written guarantees to the Syrian government that the armed groups agreed to stop violence, nor has he offered guarantees that Qatar, Saudi Arabia and Turkey will commit to stop funding and arming terrorist groups."
Those governments have denied such accusations from Syria.
The Syrian regime has consistently blamed violence in the country on "armed terrorist groups," but many world leaders have said the government is lethally cracking down on dissidents seeking true democracy and an ouster of al-Assad, whose family has ruled Syria for 42 years.
Rebels, including defectors from al-Assad's forces, have taken up arms, but their strength has often paled in comparison with the better-equipped regime troops.
"We can't drop our guns until the regime withdraws from the cities," Odah said from Istanbul. "We didn't start the mass murder. The regime started it. It has to stop killing, and then automatically we will stop."
With both the regime and rebel fighters refusing to back down until the other side does first, the quest for a cease-fire has apparently reached a stalemate.
The crisis spills over to Turkey and Lebanon
13 bodies found outside Syria school 
Syrian refugees are 'terrified' 
Al-Assad's uncle on Syria uprising 
Syria: Forces face conflict deadline While the violence has sent thousands of refugees into neighboring Turkey over several months, Monday marked the first known time in the Syrian conflict that violence crossed the border.
Selcuk Unal, a Turkish foreign ministry spokesman, said cross-border gunfire injured two Syrians and a Turkish official at the Kilis refugee camp.
"I think there was a group on the other side of the border. Some of them were wounded and they were trying to come over. Shots were fired to them as well as to the camp," Unal said.
When some in the refugee camp saw people injured at the border, "they left the camp to get the wounded people, and at that point the firing started."
Kilis governor Yusuf Odabas told CNN Turk that 13 injured Syrians were brought across the border, and two of them died.
Syria's state-run news agency SANA had no immediate mention of the incident.
On Tuesday, Annan is expected to visit Syrian refugee camps in Turkey's Hatay province, near the Sryian border.
And at Syria's western border with Lebanon, a cameraman with Lebanon's Al-Jadeed television network was killed and a reporter was wounded, according to Lebanese state-run news agency NNA.
Al-Jadeed said the cameraman, Ali Shaaban, "was killed after the news crew's vehicle came under fire by Syrian army troops while on Lebanese soil at the Northern Lebanon/Syria border."
The reporter and a second cameraman had to crawl through fields for two hours until they were rescued by residents of Wadi Khaled, said Ahmed Wehbe of Al-Jadeed.
Al-Jadeed is traditionally supportive of the regime of Syria's President Bashar al-Assad. But Wehbe said the network blames the Syrian military for the attack "because that area is under the full control of the Syrian military."
SANA said the incident at the Lebanese border took place "when the Syrian border checkpoint came under heavy gunfire from terrorist armed groups."
The SANA report also expressed condolences to the cameraman's family and colleagues, and to Al-Jadeed.
Reports of horror and executions grow
Amid the conflict, human rights groups have worked to detail what they describe as horrors carried out by al-Assad's regime.
A Human Rights Watch report released Monday documents "more than a dozen incidents (of executions) involving at least 101 victims since late 2011, many of them in March 2012," the group said.
"In a desperate attempt to crush the uprising, Syrian forces have executed people in cold blood, civilians and opposition fighters alike," said Ole Solvang, emergencies researcher for the human rights group. "They are doing it in broad daylight and in front of witnesses, evidently not concerned about any accountability for their crimes."
More than 600 people have been killed since the Syrian government signaled its intention to adhere to the Tuesday deadline to withdraw its forces from cities, according to opposition activists.
CNN cannot independently verify reports of violence and deaths, as the government has severely restricted access by international media.
The United Nations estimates that the violence in Syria has killed at least 9,000 people. The LCC puts the toll at more than 11,000.
CNN's Ivan Watson, Amir Ahmed, Yousuf Basil, Yesim Comert, Salma Abdelaziz and John King contributed to this report.
