WASHINGTON — Osama bin Laden was not carrying a weapon when he was killed by American troops in a fortified house in Pakistan, the White House said Tuesday, as it revised its initial account of the nighttime raid.

Members of a Navy Seals team burst in on Bin Laden in the compound where he was hiding and shot him in a room on an upper floor, after a fierce gun battle with other operatives of Al Qaeda on the first floor.

Bin Laden’s wife, who was with him in the room, “rushed the U.S. assaulter and was shot in the leg but not killed,” said the White House spokesman, Jay Carney, reading from the brief account, which was provided by the Defense Department. “Bin Laden was then shot and killed. He was not armed.”

Mr. Carney said that Bin Laden’s lack of a weapon did not mean he was ready to surrender, and he and other officials reiterated that this was a violent scene, that there was heavy fire from others in the house, and that the commandos did not know whether the occupants were wearing suicide belts or other explosives.