WASHINGTON – A firsthand account of the Navy SEAL raid that killed Usama bin Laden contradicts previous accounts by administration officials, raising questions as to whether the terror mastermind presented a clear threat when SEALs first fired upon him.

Bin Laden apparently was hit in the head when he looked out of his bedroom door into the top-floor hallway of his compound as SEALs rushed up a narrow stairwell in his direction, according to former Navy SEAL Matt Bissonnette, writing under the pseudonym Mark Owen in "No Easy Day." The book is to be published next week by Penguin Group (USA)'s Dutton imprint.

Bissonnette says he was directly behind a "point man" going up the stairs. "Less than five steps" from top of the stairs, he heard "suppressed" gunfire: "BOP. BOP." The point man had seen a "man peeking out of the door" on the right side of the hallway.

The author writes that bin Laden ducked back into his bedroom and the SEALs followed, only to find the terrorist crumpled on the floor in a pool of blood with a hole visible on the right side of his head and two women wailing over his body.

Bissonnette says the point man pulled the two women out of the way and shoved them into a corner and he and the other SEALs trained their guns' laser sites on bin Laden's still-twitching body, shooting him several times until he lay motionless. The SEALs later found two weapons stored by the doorway, untouched, the author said.

In the account related by administration officials after the raid in Pakistan, the SEALs shot bin Laden only after he ducked back into the bedroom because they assumed he might be reaching for a weapon.

White House spokesman Tommy Vietor would not comment on the apparent contradiction late Tuesday.

"No Easy Day" was due out Sept. 11, but Dutton announced the book would be available a week early, Sept. 4, because of a surge of orders due to advance publicity that drove the book to the top of the Amazon.com and Barnes & Noble.com best-seller lists.

The Associated Press purchased a copy of the book Tuesday.

In another possibly uncomfortable revelation for U.S. officials who say bin Laden's body was treated with dignity before being given a full Muslim burial at sea, the author reveals that in the cramped helicopter flight out of the compound, one of the SEALs called "Walt" was sitting on bin Laden's chest as the body lay at the author's feet in the middle of the cabin.

The publisher says the author used pseudonyms for all the SEALs.

Bissonnette also writes disparagingly that none of the SEALs were fans of President Barack Obama and knew that his administration would take credit for ordering the May 2011 raid. One of the SEALs said after the mission that they had just gotten Obama re-elected by carrying out the raid.

But he says they respected him as commander in chief and for giving the operation the go-ahead.

Bissonnette writes less flatteringly of meeting Vice President Joe Biden along with Obama at the headquarters of the 160th Special Operations Aviation Regiment after the raid. He says Biden told "lame jokes" no one understood, reminding him of "someone's drunken uncle at Christmas dinner."

Beyond such embarrassing observations, U.S. officials fear the book may include classified information, as it did not undergo the formal review required by the Pentagon for works published by former or current Defense Department employees.

Officials from the Pentagon and the CIA, which commanded the mission, are examining the manuscript for possible disclosure of classified information and could take legal action against the author.

In a statement provided to The Associated Press, the author says he did "not disclose confidential or sensitive information that would compromise national security in any way."

Bissonnette's real name was first revealed by Fox News and confirmed to The Associated Press.

Jihadists on Al Qaeda websites have posted purported photos of the author, calling for his murder.