3 U.S. victims killed in Libya attack IDd

BENGHAZI, Libya -- Heavily armed militants used a protest of an anti-Islam film as a cover in their deadly attack on the U.S. Consulate, screaming "God is great!" as they scaled its outer walls and descended on the main building, a witness and a senior Libyan security official said Thursday.

The detailed accounts of the rampage that killed U.S. Ambassador Chris Stevens and three other Americans came as the Libyan government said four people suspected in the attacks had been arrested and more were being sought.

In Washington, U.S. officials briefed on the investigation said the Libyan-based militant group Ansar al Sharia is the leading suspect for carrying out the violence, possibly with help from al-Qaida's main African-based offshoot, al-Qaida in the Islamic Maghreb.

Eastern Libya's deputy interior minister, Wanis el-Sharef, said the attack in Benghazi was two-pronged. Hours after the crowd stormed the consulate Tuesday night, the militants raided a safe house just as U.S. and Libyan security arrived to evacuate the staff.

Also killed in the attack were information management officer Sean Smith, private security guard Glen Doherty and Tyrone Woods, a former Navy SEAL who has protectedAmerican diplomatic personnel in dangerous posts from Central America to the Middle East since 2010.

Stevens and one of the other Americans were killed during the initial violence, as plainclothes Libyan security were moving the consulate's staff to the safe house about a mile away, el-Sharef said. The ambassador probably died of asphyxiation after a grenade explosion that started a fire, he said.

The second assault several hours later targeted the safe house, a villa inside the grounds of the city's equestrian club, killing the two other Americans and wounding a number of Libyans and Americans. That the attackers knew the safe house's location suggests a "spy" inside the security forces tipped them off, el-Sharef said.

U.S. officials have not confirmed el-Sharef's account. They have spoken of an attack on the consulate's annex that killed two Americans, but said their report was still preliminary.

The U.S. officials have said Stevens became separated from others during an evacuation and staffers and security who tried to find him were forced to flee because of flames, smoke and gunfire.