U.S. lawmakers are set to hold a hearing into the attack last month on the U.S. consulate in Benghazi, Libya, which left the U.S. ambassador and three other Americans dead.
Ahead of the hearing Wednesday by the Republican-led House Oversight and Government Reform Committee, senior State Department officials gave reporters a detailed account of the attack on September 11.
The officials, speaking on the condition of anonymity, said there was "nothing unusual" at the consulate site before the attack, and that they did not conclude the assault was triggered by protests against an anti-Islam video.
The government initially linked the attack to protests, but administration officials later said it was a planned terrorist attack. The State Department is conducting its own investigation into the incident.
Among those testifying Wednesday is the former chief security officer for U.S. diplomats in Libya. A memo detailing earlier testimony to a congressional investigator says Eric Nordstrom sent cables to Washington in March and July asking for more security officers in Benghazi, but got no response.
He said Charlene Lamb, a State Department official who will also testify Wednesday, believed the post did not need more security because it was equipped with a residential safe haven that could be used in case of emergency.
In the account given late Tuesday, the State Department officials said Ambassador Christopher Stevens, embassy officer Sean Smith and a security agent retreated to the safe haven after a large group of armed men entered the compound.
The attackers set fire to furniture inside the building, filling it with smoke that later forced the three men to flee. They became separated, and security forces who arrived to assist them found only the security agent on the roof and Smith's body.
The security forces were unable to find the ambassador, and retreated with the remaining people at the compound to an annex that also came under fire before they were able to evacuate.