After days of protests and related violence, concerns are growing that furor over an anti-Islam video could intensify even more Friday -- threatening U.S. interests abroad and at home.

People have taken to the streets in 10 nations and the Indian-controlled region of Kashmir, according to U.S. Sen. Dianne Feinstein, railing against "Innocence of Muslims" and the nation where it was produced, the United States. This outrage, and danger to Americans, could worsen in the coming days, the U.S. Department of Homeland Security and FBI warned Thursday in a joint intelligence bulletin.

"The risk of violence could increase both at home and abroad as the film continues to gain attention," the U.S. agencies said. "Additionally, we judge that violent extremist groups in the United States could exploit anger over the film to advance their recruitment efforts."

Worries about Friday, in particular, stem from the fact Muslims hold weekly prayers that day -- and may congregate afterward and march on U.S. diplomatic missions.

"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 U.S. official said.

The ongoing unrest centers on an obscure 14-minute film trailer that mocks Islam's prophet.

Posted in July on YouTube, it got more notice recently after Egyptian television aired segments and anti-Islam activists promoted it online. Numerous questions surround the film, which includes cartoonish scenes of Mohammed as a womanizer, child molester and ruthless killer.

According to a FBI/Homeland Security joint statement, the film's producer identified himself to news media as an Israeli -- an assertion Israel's government denies -- and falsely claimed the movie was financed with help from more than 100 Jewish donors.

While he'd been identified in July 2011 by various names, including Sam Bassiel, federal officials now say they believe the filmmaker's name is Nakoula Basseley Nakoula. He was convicted in 2009 of bank fraud, with the indictment from the U.S. Attorney's Office listing seven aliases.

A production staffer said he believed the filmmaker was a Coptic Christian who also went by the name Abenob Nakoula Bassely.

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.

In addition to stressing there's no excuse for violence targeting U.S. diplomatic missions, Secretary of State Hillary Clinton has called the video "disgusting and reprehensible" and said it appears to aim "to denigrate a great religion and to provoke rage."

Still, condemnations of the film and calls by leaders of largely Muslim countries not to assault U.S. diplomatic missions haven't stopped throngs from demonstrating, at times violently.

Protests rage against inflammatory anti-Islam film trailer

Small and large demonstrations have occurred in recent days all around North Africa and the Middle East. While some protesters say they have not seen any of the online film, they were incensed by reports of its depiction of the Prophet Mohammed.

Many of them directed their anger, too, at the U.S. government and its Israeli allies. In Cairo, for instance, a photo showed a man standing over chalk-writing, in Arabic, that read, "Remember your black day 11 September."

Here are details about various protests:

-- In Yemen, demonstrators breached a security wall at the U.S. Embassy as several thousand people protested outside. Four protesters died during clashes with security forces outside the embassy, according to Yemeni security officials.

Twenty-four security force members were reported injured, as were 11 protesters, according to Yemen's Defense Ministry, security officials and eyewitnesses.

-- In Egypt, site of one of the largest, longest-lasting protests, at least 13 civilians and six police officers were injured Thursday, according to Egyptian government officials. Throngs continued to pack the area in front of the Cairo embassy on Friday morning, as a large fire burned and security guarded the area.