“They were in a threatening and hostile environment the entire time,” one American official said.

When the commandos moved into the main house, they saw the courier’s brother, who they believed was preparing to fire a weapon. They shot and killed him. Then, as they made their way up the stairs of the house, officials said they killed Bin Laden’s son Khalid as he lunged toward the Seal team.

When the commandos reached the top floor, they entered a room and saw Osama bin Laden with an AK-47 and a Makarov pistol in arm’s reach. They shot and killed him, as well as wounding a woman with him.

The firefight over and Bin Laden dead, the team found a trove of information and had the time to remove much of it: about 100 thumb drives, DVDs and computer disks, along with 10 computer hard drives and 5 computers. There were also piles of paper documents in the house.

The White House declined to release any additional details about the operation, saying that further information would jeopardize the military’s ability to conduct clandestine operations in the future. The administration’s reticence came after it was forced on Tuesday to correct parts of its initial account of the raid, including assertions that Bin Laden had used his wife as a “human shield.”

“We’ve revealed a lot of information; we’ve been as forthcoming with facts as we can be,” Mr. Carney said.

Mr. Carney said the president expressed doubts early on about releasing the photos, but consulted his senior advisers. All of them, Mr. Carney said, voiced concerns about the risks. Based on its monitoring of worldwide reaction to the announcement of Bin Laden’s death, Mr. Carney said, the administration also concluded that most people viewed the reports of his death as credible and that publicizing photos would do little to sway those who believed it was a hoax.