U.S. Ambassador to Libya Christopher Stevens and three other staffers were killed in an attack on the Benghazi consulate late Tuesday. 

The Guardian reports California-born Stevens and the three other staff members were killed in a rocket attack on the diplomat's car.

According to Reuters, Islamist gunmen carried out the attack in outrage sparked by a film they said mocked the Prophet Mohammed.

See the trailer for the film below.

Filmmaker Sam Basile said the controversial movie had been shown only once in a sparsely filled Hollywood theater earlier this year.

The Guardian has been updating a live blog of developments since news broke Tuesday night. As the gravity of the situation became apparent, Secretary of State Hillary Clinton issued a statement:

"Some have sought to justify this vicious behavior as a response to inflammatory material posted on the Internet. The United States deplores any intentional effort to denigrate the religious beliefs of others. Our commitment to religious tolerance goes back to the very beginning of our nation. But let me be clear: There is never any justification for violent acts of this kind."

She later followed up with a tribute to the dead:

"It is with profound sadness that I share the news of the death of four American personnel in Benghazi, Libya yesterday. Among them were United States Ambassador to Libya Chris Stevens and Foreign Service Information Management Officer, Sean Smith. We are still making next of kin notifications for the other two individuals. Our hearts go out to all their families and colleagues.

"…All the Americans we lost in yesterday’s attacks made the ultimate sacrifice. We condemn this vicious and violent attack that took their lives, which they had committed to helping the Libyan people reach for a better future."

President Obama also condemned the attack, but not before candidate Romney had a chance to criticize the White House' response. Romney told reporters this morning he couldn't stand by the administration's "sympathizing." He has since been blasted for turning the tragedy into a campaign opportunity.  

Read more of Neon Tommy's Libya coverage here.

Reach Executive Producer Catherine Green here; follow her here.