The American ambassador to Libya and three other diplomatic staff members died Tuesday in an attack by an armed mob at the US consulate in Benghazi, the Libyan interior ministry said Wednesday (September 12th).

Witnesses said the mob looted the consulate before setting it on fire. Ambassador J. Christopher Stevens and three other US officials died in the blaze.

The other staff members "were evacuated and are safe and sound", Deputy Interior Minister Wanis al-Sharif said.

According to the ministry's security commission, rocket-propelled grenades were fired at the consulate from a nearby farm.

"I condemn these barbaric acts in the strongest possible terms. This is an attack on America, Libya and free people everywhere," Libyan Deputy Prime Minister Mustafa Abushagur said via Twitter. Ambassador Stevens had been "a friend of Libya", he said.

"We present our apologies to the United States, the American people and the entire world for what happened," Mohamed al-Megarief, president of Libya's General National Congress, told reporters in the capital, Tripoli.

US Secretary of State Hillary Clinton confirmed the deaths on Wednesday morning. "I had the privilege of swearing in Chris [Stevens] for his post in Libya only a few months ago," she said. "He spoke eloquently about his passion for service, for diplomacy and for the Libyan people. As the conflict in Libya unfolded, Chris was one of the first Americans on the ground in Benghazi. He risked his own life to lend the Libyan people a helping hand to build the foundation for a new, free nation."

She added in verbal remarks that US-Libya relations would not be impacted. "The friendship between our two countries born out of shared struggle will not be another casualty of this attack."

US President Barack Obama condemned the attack and promised enhanced security. "While the United States rejects efforts to denigrate the religious beliefs of others, we must all unequivocally oppose the kind of senseless violence that took the lives of these public servants," he said. "I have directed my Administration to provide all necessary resources to support the security of our personnel in Libya, and to increase security at our diplomatic posts around the globe."

Speaking at the White House, President Obama thanked Libyans for the role they played in responding to the attack. "Libyan security personnel fought back against the attackers alongside the Americans," he said. "Libyans helped some of our diplomats find safety and they carried Ambassador Stevens' body to the hospital where we tragically learned he had died."

"It's especially tragic Chris Stevens died in Benghazi, because it's a city he helped to save," the president added.

The protest erupted over an independent film, "Innocence of Muslims", deemed offensive to the Prophet Mohammed. The Benghazi incident came a few hours after an attack on the US embassy in Cairo, in which rioters replaced the US flag with a black Islamic flag. Egyptian police managed to restore order without resorting to violence.