A video has surfaced showing a group of Libyans pulling U.S. ambassador Chris Stevens out from the wreckage of the

Sept. 11 consulate attack that killed him and three other Americans.

"I was filming the video, and I thought it was an American," freelance videographer Fahed al-Bakush told CNN. "But I thought it was a driver, or a security guard. "I never thought it was the ambassador."

The four men were killed during an attack on the U.S. consulate in Benghazi, during a wave of protests around the Middle East sparked by a 14-minute video attacking both Islam and its central figure, the prophet Muhammad.

Mohamed Al-Magariaf, the head of Libya's national congress, said the attack itself, however, was a calculated assault. The Associated Press also reports that it obtained a CIA memo suggesting the original demonstration "evolved into a direct assault" by extremist groups.

In the video, a group of men can be seen pulling an unconscious man al-Bakush said is Stevens out of the building. Al-Bakush said the man had a faint pulse and his mouth was black from inhaling soot. After discovering him, the men chanted "Alive! Alive! God is Great!"

Ahmed Shams, a freelance photographer who works with al-Bakush, corroborated his account to the AP, saying the group carried the unconscious man to a car and drove him to a nearby hospital.

"There was no security, no ambulances, nothing to help," he said.

The doctor who treated the man, Zaid Abu Zeid, told the network he didn't know the man brought to him as a code blue -- patient in need of resucitation -- was the ambassador. Abu Zeid said he tried to revive him for 45 minutes, to no avail.

A spokesperson for the U.S. State Department, Victoria Nuland, did not confirm that the man shown in the video was Stevens, and said it was not clear whether it accurately shows what happened on the night he was killed.

"This video ... is going to be part and parcel of this investigation," Nuland said. "But I'm not in a position to confirm what, who, where and whether it has any value."

Al-Bakush's description of the video, published by CNN on Tuesday, can be seen below.