(Updated 9:26 am., Sept. 13, PHL time) BEIRUT - The US ambassador to Libya and three other embassy staff were killed in a rocket attack on Tuesday night that targeted his car in the eastern Libyan city of Benghazi, a Libyan official said on Wednesday.

"The American ambassador and three staff members were killed when gunmen fired rockets at them," the official in Benghazi told Reuters. Asked about the deaths, a US Embassy employee in Tripoli said: "We have no information regarding this." The employee said the embassy could confirm the death of one person.

In a separate report, Agence France-Presse noted, "The American ambassador to Libya, J. Christopher Stevens, and three officials were killed when a mob attacked the US consulate in the eastern city of Benghazi," citing an interior ministry report.

"The ambassador was killed along with three other officials," said Wanis al-Sharif, the deputy minister of the interior. Stevens' death in Tuesday's attack was confirmed in a tweet by Mustafa Abu Shagur, the deputy prime minister.

Another Reuters report said US President Barack Obama  has vowed to bring to justice the killers of the US ambassador and three other diplomats in Libya as he sought to avoid election-year fallout from an attack that cast a spotlight on his administration's handling of "Arab Spring" unrest.

Meanwhile, an Agence France-Presse report said the US dispatched two destroyers to Libya and deployed a Marine team to bolster security at its Tripoli embassy also on Wednesday.

Safer venue 

The Libyan official said the US ambassador had been on his way to a safer venue after protesters attacked the US Consulate in Benghazi and opened fire, killing a staff member, in protest at a U.S. film that they deemed blasphemous to the Prophet Mohammad.

The official said the ambassador and three other staff were killed when gunmen fired rockets at his car. He said the US Embassy had sent a military plane to transport the bodies to Tripoli to fly them to the United States.

Gunmen assaulted the Benghazi compound on Tuesday evening, clashing with Libyan security forces, who withdrew under heavy fire. The attackers fired at the buildings while others threw handmade bombs into the compound, setting off small explosions. Small fires were burning around the compound.

The assault followed a protest in neighboring Egypt where demonstrators scaled the walls of the US embassy, tore down the American flag and burned it during a protest over the same film which they said insulted the Prophet Mohammad. - AFP/Reuters