Protesters chant slogans during a march to the U.S. Embassy in Sanaa, Yemen, on Thursday, September 13. One protester was killed in clashes when Yemeni security forces dispersed hundreds of demonstrators who gathered around and inside the U.S. Embassy in Sanaa as part of widespread anger in at least 11 countries over a film ridiculing Islam's Prophet Mohammed. 
A protester shouts slogans after sustaining injuries from a confrontation with riot police who fired tear gas outside the U.S. Embassy in Sanaa on Thursday. 
Protesters carry flags that read "There is no God but Allah, Mohammed is Allah's messenger" and chant slogans during a protest against a film they consider blasphemous to Islam and insulting to the Islamic prophet in Tripoli, Lebanon, on Thursday. 
Palestinians protest against the movie "Innocence of Muslims" in front of the Legislative Council in Gaza City on Thursday. 
Iranian demonstrators chant anti-American slogans during a demonstration on Thursday in front of the Swiss Embassy, which serves as the U.S. interests section in Iran, in Tehran. 
An Iranian police officer shows a victory sign during Thursday's demonstration in Tehran. 
Supporters of Sunni Muslim Salafist leader Ahmad al-Assir burn an Israeli and a U.S. flag during a protest in Sidon, Lebanon, on Thursday. 
Kuwaiti police stand guard as hundreds of demonstrators protest near the U.S. Embassy in Kuwait City on Thursday. 
Arab-Israeli Muslim men wave green Islamic flags with the Muslim profession of belief: "There is no God but God and Mohammed is the prophet of God" during a protest in front of the U.S. Embassy on Thursday in Tel Aviv, Israel. 
Egyptian protesters throw stones at riot police during clashes near the U.S. Embassy in Cairo on Thursday. 
Riot police take cover from stones thrown by protesters on Thursday. 
Egyptian protesters help a man who inhaled tear gas during clashes at the U.S. Embassy in Cairo on Thursday. 
A burned-out pickup sits between Egyptian protesters and riot police in Cairo on Thursday. 
Egyptian protesters take cover during clashes with riot police on Thursday. 
An Egyptian protester wears a makeshift mask and helmet for protection while fighting riot police on Thursday. 
Egyptian protesters run for cover from tear gas fired by riot police during clashes on Thursday. 
An Egyptian riot police officer fires tear gas toward protesters during clashes Thursday with police near the U.S. Embassy in Cairo. Muslims throughout the Middle East have been demonstrating for three days outside U.S. missions, denouncing a film deemed offensive to Islam. 
Iraqi protesters burn Israeli and U.S. flags during a protest Thursday. The U.S. ambassador to Libya, J. Christopher Stevens, and three others were killed during a protest outside the U.S. Consulate in Benghazi, Libya, on Tuesday. 
Egyptian protesters clash with riot police Thursday near the U.S. Embassy in Cairo. 
Iranians protest against a film mocking Islam near the Swiss Embassy in Tehran on Thursday. Up to 500 people chanted "Death to America!" and death to the director of the movie, which was made in the United States. The demonstration ended peacefully in two hours. 
An Egyptian protester throws a tear gas canister at riot police Thursday during clashes near the U.S. Embassy in Cairo. 
Police use tear gas on crowds protesting Thursday outside the U.S. Embassy in Cairo. 
The U.S. Consulate in Benghazi is seen in flames Tuesday, September 11. 
A vehicle and the surrounding area are engulfed in flames after it was set on fire inside the compound on Tuesday. 
A protester reacts as the U.S. Consulate in Benghazi is seen in flames Tuesday night. 
Yemeni protesters gather around a fire Thursday during a demonstration outside the U.S. Embassy in the capital of Sanaa. Yemeni forces fired warning shots to disperse the thousands of protesters approaching the main gate of the mission. 
Yemeni protesters try to break the security camera at the U.S. Embassy in Sanaa on Thursday. 
Egyptians shout slogans during a protest in front of the U.S. Embassy in Cairo. 
Egyptian protesters gather in front of the U.S. Embassy the morning after it was vandalized by protesters during a demonstration on Wednesday in Cairo. 
Protesters shout outside the U.S. Embassy in Tunis, Tunisia, on Wednesday, September 12. 
A group of protesters attend a demonstration outside the U.S. Embassy in Tunis on Wednesday. 
A demonstrator walks on a U.S. flag during a Wednesday's demonstration at the U.S. Embassy in Tunis. 
People inspect the damage at the U.S. Consulate in Benghazi, Libya, on Wednesday, the day after four people were killed. 
Egyptian demonstrators continue to stake out the U.S. Embassy in Cairo on Wednesday. 
Police confront protesters praying in front of the U.S. Embassy in Casablanca, Morocco, during a rally against the anti-Islam film on Wednesday. 
Moroccan women gather near the U.S. Embassy in Casablanca on Wednesday. 
A Palestinian man holds a placard praising Islam's prophet Mohammed during a demonstration against the film on Wednesday in front of the United Nations headquarters in Gaza City. 
Palestinian men burn the American flag during Wednesday's demonstration in Gaza City. 
A man waves his rifle as buildings and cars are engulfed in flames inside the U.S. Consulate compound in Benghazi, Libya, late on Tuesday, September 11. 
The U.S. Consulate in Benghazi is set on fire during a protest. Armed gunmen attacked the compound on Tuesday evening, clashing with Libyan security forces before the latter withdrew as they came under heavy fire. 
Protesters destroy an American flag pulled down from the U.S. Embassy in Cairo, Egypt. 
People stand around a drawing that says "Remember your black day 11 September" during the protest in Cairo. 
People shout and light flares in front of the U.S. Embassy in Cairo. 
People shout in front of the U.S. Embassy in Cairo. 
Protesters pull down a U.S. flag. 
Thousands were angered by the controversial film. 
Demonstrators yell outside the U.S. Embassy. 
Egyptian riot police stand guard as protesters climb down from the wall. 
An Egyptian protester waves a black flag inscribed with the Muslim profession of faith -- "There is no God but God, and Mohammed is the prophet of God" -- as he stands above the door of the U.S. Embassy. 
Protesters gather along the U.S. Embassy wall. 
- The United States has ordered increased security at its diplomatic facilities
- "We are in a full-court press at every single one of the posts," an official says
- Clashes between protesters and police flared for a fourth day in Cairo
- Libyan authorities say they have made an arrest in the death of four Americans
(CNN) -- The United States braced Friday for a fourth day of protests targeting its diplomatic facilities in the Middle East and elsewhere as furor in the Islamic world continued over a film that characterizes Prophet Mohammed as a womanizing buffoon.
Worries, in particular, stemmed from fears that calls for large, peaceful demonstrations on Friday, the traditional day of protest following the weekly Muslim prayer, would turn violent.
"We are in a full-court press at every single one of the posts in the Middle East and anywhere else there is any chance of demonstrations after Friday services to make sure nothing bad happens. And to have the security in place in case bad things do happen," one senior administration official said Thursday. The official, who was not authorized to publicly discuss the issue, spoke on condition of anonymity.
The ongoing unrest centers on an obscure 14-minute film trailer that mocks the Mohammed as a womanizer, child molester and ruthless killer. Posted in July on YouTube, the clip received attention after it was aired on Egyptian television and anti-Islam activists promoted it online.
On Tuesday, the same day people protesting the film stormed the U.S. Embassy in Cairo, the U.S. Consulate in Benghazi was attacked -- leading to the deaths of U.S. Ambassador Chris Stevens, State Department computer expert Sean Smith, and security officers Glen Doherty and Tyrone Woods, both former Navy SEAL commandos.
As word of video spreads, so do protests
People have taken to the streets in 11 nations and territories, including Egypt where protesters squared off Friday with security forces for a fourth day of protests near the U.S. Embassy in Cairo.
The film permit for "Innocence of Muslims" has been withdrawn at the request of federal authorities, who cited public safety concerns, according to Film LA, Inc., the non-profit agency that oversees production in the Los Angeles area.
By withdrawing the permit, copies of the film cannot be released by the agency.
Federal authorities have discounted as false a producer's claims to news outlets that he was an Israeli -- an assertion Israel's government denies -- who made the movie with financing with help from more than 100 Jewish donors.
The protests abroad and the false claim by the producer about Jewish donors caused the FBI and Department of Homeland Security to warn in a joint bulletin of a risk of an increase in violence both "at home and abroad as the film continues to gain attention."
Four days of unrest
Outside the U.S. Embassy in Cairo, riot police sporadically clashed with protesters for a fourth straight day after a failed attempt to disperse the demonstrators shortly after dawn on Friday.
Police armed with shields and batons, backed by an armed personnel carrier, rushed a group of several hundred protesters, a move that came after U.S. President Barack Obama warned that relations with Egypt will be shaped by how the country responds to the violence.
"I don't think that we would consider them an ally, but we don't consider them an enemy," Obama told Telemundo in an interview that aired Thursday night.
If Egypt takes actions, Obama said, that "indicate they're not taking responsibilities, as all other countries do where we have embassies, I think that's going to be a real big problem."
Authorities have arrested 37 people in connection with the violence, according to Egypt's state-run news agency.
A see-saw battle that began Thursday between protesters and the police raged through most of the night, with demonstrators throwing Molotov cocktails and rocks and authorities responding with tear gas.
Sporadic gun fire could be heard in the area around the U.S. Embassy.
At least 224 people were injured, according to Egyptian state television, Nile TV. Among the injured were 31 police officers, according to the Ministry of the Interior.
Here are the details about various protests:
--In Syria, hundreds gather outside the U.S. Embassy in Damascus. Protesters waved placards that condemned the film and blamed the the U.S. administration for allowing the production and broadcast of the film, according to the state-run Syrian Arab News Agency
--In Egypt, the Muslim Brotherhood called for a large, peaceful protest to denounce the film.
--In Iran, the Islamic Propagation Coordination Council called for nationwide rallies on Friday to protest against the film and what it is calling a U.S.-backed plot against Muslims, according to state-run news IRNA.
So far, the violence has not spread to Afghanistan, where there is a high potential for outrage to erupt into destabilizing chaos. Obama and his Afghan counterpart, Hamid Karzai, have expressed their commitment to prevent that from happening.
The Afghan government has ordered an indefinite block of YouTube to prevent people there from watching the clips and staging violent protests. YouTube has already restricted access to the video.
Arrest in Libya
Sources tracking militant Islamist groups in eastern Libya say the attack that killed Stevens and three other Americans was most likely carried out by a pro-al Qaeda group. Obama has vowed "justice will be done."
The first of two U.S. warships, carrying guided missiles, has arrived off the coast of Libya, and unmanned drones have been sent to help search for the killers.
A group of Marines called a Fleet Antiterrorism Security Team was deployed to Libya to help secure U.S. facilities, said two U.S. officials, who spoke on condition of anonymity because they were not authorized to release the information.
About 50 Marines arrived in the country Wednesday, the officials said.
There has been at least one person arrested in connection with the attack at the consulate in Benghazi, Libyan Prime Minister Mustafa Abushagur told CNN.
He said authorities actively pursuing "three or four" more after examining video from the scene and talking with witnesses, though
Libyan Deputy Interior Minister Wanis al-Sharif, according to state-run LANA news agency, said "some individuals" suspected in the case were in custody.
CNN's Arwa Damon, Ben Wedeman, Hamdi Alkhshali, Brian Walker and Elise Labott contributed to this report.
