- NEW: People "did not trade the tyranny of a dictator for the tyranny of a mob," Clinton says
- NEW: Tunisian troops help U.S. Marines protect U.S. Embassy in Tunis
- Muslims angry about film protest in more than a dozen countries
- Militants breached an international peacekeeping base in Egypt's northern Sinai
(CNN) -- As anti-American furor raged in the home of the Arab Spring, the top U.S. diplomat gave a stern warning Friday to countries where the unrest has been most pronounced: Stop the violence and seek justice against those attacking diplomatic missions, or else the United States will.
Thousands of Muslims have taken to the streets in recent days.
Many have fumed over what Secretary of State Hillary Clinton described Friday as an "awful Internet video that we had nothing to do with" -- an inflammatory anti-Islam film posted online this summer, and publicized in recent days. The 14-minute film trailer, which was privately produced in the United States led by a man federal officials identified as Nakoula Basseley Nakoula, mocks the Prophet Mohammed as a womanizer, child molester and ruthless killer.
These protesters, while just a fraction of their nations' total populations, have been part of clashes that have left many dead, including the U.S. ambassador to Libya and three others killed in an attack Tuesday in Benghazi, Libya.
Clinton said these attacks are misguided, and fly in the face of the better society many in these countries recently fought for when they overthrew authoritarian rulers.
"The people of Egypt, Libya, Yemen and Tunisia did not trade the tyranny of a dictator for the tyranny of a mob," she said Friday during a ceremony in which the bodies of the four killed in Benghazi returned to the United States.
"Reasonable people and responsible leaders in these countries need to do everything they can to restore security and hold accountable those behind these violent acts. And we will ... keep taking steps to protect our personnel around the world."
Two years ago, the self-immolation of street vendor Mohamed Bouazizi set off a wave of popular unrest that soon led to the downfall of Tunisia's longtime leader, President Zine El Abidine Ben Ali.
On Friday, hundreds of demonstrators were back on the streets of the Mediterranean city, setting their sights on the U.S. Embassy. They burned cars, stormed the complex and replaced the U.S. flag with their own black banner, according to eyewitness accounts.
Three people were killed and 28 others wounded outside the embassy, Tunisia's state TV reported. U.S. Ambassador Jabob Walles and his staff got protection from U.S. Marines as well as members of the Tunisian Anti-Terror Brigade Force, one of its members told CNN.
But anti-American protests, and violence, were hardly confined to Tunisia. Here's a breakdown of where things stand around the Muslim world:
-- In the Egyptian capital of Cairo, a running battle between police and protesters continued into its fourth day. There was a peaceful demonstration at 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.
-- 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.
-- Afghanistan saw its first demonstrations Friday, despite the government's attempts to prevent riots. Hundreds 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 U.S. 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 also were protests in Iran, Iraq, London, Jerusalem, Nigeria and the southern Indian city of Chennai. Protesters congregated in Pakistan and Turkey to express their opposition to the online film.
These demonstrations were not unexpected: On Thursday, 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."
And days before violent protests Tuesday in Egypt, the U.S. Embassy in Cairo was warned by the American intelligence community of concerns about the "Innocence of Muslims" film that sparked the outrage, 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.
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.
Latest on the investigation into U.S. ambassador's killing
Sources tracking militant Islamist groups in eastern Libya say the Tuesday attack that killed Ambassador Chris 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.
Since the Benghazi attack, the U.S. announced it will fly unmanned drones over Libya and dispatch two warships carrying guided missiles -- the first of which has already arrived off the coast of Libya.
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.
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.
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.
CNN's Harmeet Singh, Kareem Khadder, Mohammed Tawfeeq, Arwa Damon, Ben Wedeman, Hamdi Alkhshali, Brian Walker and Elise Labott, and journalists Masoud Popalzai, Zied Mhirsi, Isma'il Kamal Kushkush contributed to this report.