CNN-The birthplace of the Arab Spring seethed Friday as anti-American rage sparked by an online film that insulted Islam's prophet boiled over across the Muslim world.
Hundreds of demonstrators turned out in Tunisia, the country where the self-immolation of a street vendor nearly two years ago set in motion widespread protests that toppled dictators in the region.
But Friday was an entirely different scene as protesters set their sights on the U.S. Embassy in Tunis, burning cars, storming the complex and replacing the U.S. flag with their own black banner, according to eyewitness accounts. Three people were killed and 28 others were wounded outside the embassy, Tunisia's state TV reported.
Aware that protests were planned in several Islamic countries Friday -- the Muslim holy day -- the United States beefed up security at its embassies and consulates across the Middle East.
The current unrest began Tuesday when outrage over a 14-minute American-made online video that mocks the Prophet Mohammed as a womanizer, child molester and ruthless killer sparked rioting at the U.S. Consulate in Benghazi, Libya.
Four American consulate staffers were killed, including U.S. Ambassador Chris Stevens. The same day, protesters stormed the U.S. Embassy in Cairo, although there were no reported casualties.
U.S. officials suspect that a group sympathetic to al Qaeda used the protests over the film as cover for the complex and well-coordinated attack on the U.S. Consulate in Benghazi.
Days before Tuesday's protests, the U.S. Embassy in Cairo was warned by the American intelligence community of concerns about the video, a U.S. official told CNN. The cable sent to the embassy did not mention a specific threat. It only warned about the existence of the online movie and the fact that it was gaining attention.
Since then, there have been more violent protests an outrage over the online film, which YouTube has restricted in certain countries.
Here's a breakdown of where things stand:
People have taken to the streets in the Muslim world and other locations to show their outrage about the film.
-- In the Egyptian capital, a running battle between police and protesters continued into its fourth day. There was a peaceful demonstration at Cairo's Tahrir Square, but unrest erupted outside the U.S. Embassy in Cairo as riot police clashed sporadically with protesters. The Interior Ministry reported dozens of arrests and injuries.
-- In Egypt's northern Sinai, Islamist Bedouins staged a protest, a security official said. Militants carrying automatic weapons breached a base housing international peacekeeping troops and burned trucks and a watch tower. The armed clashes injured at least four troops and an Islamist Bedouin. The 1,500-troop mission has supervised the security of the Egyptian-Israeli peace treaty since 1979.
Read more about clashes in Cairo
-- In Sudan's capital, Khartoum, protesters managed to get inside the German Embassy and pull down a German flag before police with tear gas forced the crowds to retreat.
-- In Yemen, police opened fire Friday to stop protesters from reaching the U.S. Embassy in Sanaa, eyewitnesses told CNN. Twenty-four security force members were reported injured, as were 11 protesters, according to Yemen's Defense Ministry, security officials and eyewitnesses.
-- Afghanistan saw its first demonstrations Friday, despite the government's attempts to block the online video from sparking riots. Hundreds of demonstrators in eastern Nangarhar province burned a U.S. flag and chanted "Death to America" and "We condemn the film." The demonstration lasted about an hour and ended peacefully, a local official said. The Afghan government has ordered an indefinite block of YouTube to prevent people there from watching the clips and staging violent protests.
In Gaza, several thousand people gathered after Friday prayers and chanted anti-American and anti-Israeli slogans. Protesters burned American and Israeli flags, as well as effigies of President Barack Obama.
-- In Syria, hundreds of protesters outside the U.S. Embassy in Damascus waved placards that condemned the film and blamed the U.S. administration for allowing the production and broadcast of it, according to the state-run Syrian Arab News Agency.
-- In Lebanon, hundreds of demonstrators took to the streets in the northern city of Tripoli, where they attacked and burned down a KFC restaurant. One person was killed and 25 others were wounded in scuffles between protesters and security forces.
There were also protests in Iran, Iraq, London, Jerusalem, Nigeria and the southern Indian city of Chennai. Peaceful protesters congregated in Pakistan and Turkey to express their opposition to the online film.
The FBI and the U.S. Department of Homeland Security warned there could be more violence "at home and abroad as the film continues to gain attention."
The online video generated little interest when it was first posted in July on YouTube, but it received global attention after it was aired recently on Egyptian television and promoted by anti-Islam activists online.
Jewish groups mad about early reports on anti-Islam film
U.S. authorities have discounted as false a producer's claims to news outlets that the filmmaker was an Israeli who made the movie with financing from more than 100 Jewish donors. Israel's government denies that the film's maker is Israeli.
New details emerge about mystery filmmaker
Latest on the investigation into U.S. ambassador's killing
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 that "justice will be done."
Four people have been arrested in connection with the attack, although they were not directly tied to the killings, said Monem Elyasser, the chief aide to the Libyan prime minister.
Elyasser did not release the identities nor did he detail the allegations against the four people in custody.
The evidence leading to the arrests was based partly on witnesses, but "mostly pictures that were taken around the compound at that time," Libyan Prime Minister Mustafa Abushagur told CNNI's Christiane Amanpour.
Security beefed up
Officials are working to bulk up security in hotspots and react properly in areas where violence has popped up.
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 of the Americans.
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.
More security forces are being deployed to Yemen as well.
"Although these security forces are equipped for combat, these movements have been undertaken solely for the purpose of protecting American citizens and property. These security forces will remain in Libya and in Yemen until the security situation becomes such that they are no longer needed," Obama said.
A senior State Department official said the United States is working with the Tunisian and Sudanese governments "to ensure the necessary resources to deal with the situation at our missions there."
United Nations High Commissioner for Human Rights Navi Pillay on Friday urged religious and political leaders to restore calm amid protests "in some 15 or more countries across the world."
She condemned the killings at the U.S. Consulate in Libya and the ensuing violence over what she called a "malicious and deliberately provocative" film about Muslims.
What Muslim nations' leaders are saying -- and not -- about violence
Pillay recalled the killings of more than 20 people, including seven U.N. staffers, in Afghanistan last year after what she called "another deeply provocative act by a pastor in Florida." That was a reference to the burning of Qurans by American pastor Terry Jones.
"It is deeply tragic and reprehensible that people who have nothing whatsoever to do with these disgraceful stunts should lose their lives to enraged mobs and extremists in countries such as Libya and Afghanistan," she said.