A US official has been killed and others wounded in Libya as an armed mob protesting over a film they said offended Islam attacked the US consulate in Benghazi.
Libya's Supreme Security Committee spokesman said: "One American staff member has died and a number have been injured in the clashes."
But Abdel Monem al Hurr said he did not know the exact number of injured.
Armed gunmen attacked the compound on Tuesday evening, clashing with Libyan security forces before the latter withdrew as they came under heavy fire.
Reporters on the scene said they could see looters raiding the compound, walking off with desks, chairs and washing machines.
Libya's deputy interior minister Wanis al Sharef said that other staff members were evacuated "and are safe and sound".
In the Egyptian capital, Cairo, earlier, protesters climbed the walls of the US embassy, tore down the American flag and burned it.
The protests were sparked by outrage over a video being promoted by an extreme anti-Muslim Egyptian Christian campaigner in the US, which the demonstrators says insults the Prophet Mohammed.
The US condemned the attack in Benghazi, amid reports that the mission had been set on fire and targeted with rocket-propelled grenades.
"We can confirm that our office in Benghazi, Libya, has been attacked by a group of militants," State Department spokeswoman Victoria Nuland said.
"We condemn in strongest terms this attack," she added in a statement issued before reports of the death, which came on the 11th anniversary of the 9/11 attacks.
US officials were working with the Libyans to secure the compound, Ms Nuland said, adding that the earlier protest in Cairo had ended.
Mr al Hurr said the grenades were fired from a nearby farm at the building.
Security forces and the interior ministry were trying to contain the situation, he added.
The film apparently depicts Mohammed as a fraud, showing him having sex and calling for massacres.
Many Muslims consider any depiction of the prophet to be offensive.
But officials said it remained unclear whether the two protests in Benghazi and Cairo had been coordinated or whether they were linked.
"We cannot confirm any connection between these incidents," said a senior State Department official, asking to remain anonymous.