WASHINGTON (AP) - Only one of the five people killed in the raid that got Osama bin Laden was armed and fired any shots, a senior defense official said Thursday, acknowledging that the new account differs greatly from original administration portrayals of a chaotic, intense and prolonged firefight.

The sole shooter in the al-Qaida leader's Pakistani compound was quickly killed in the early minutes of the commando operation, before the team of Navy SEALs swept through the house and shot the others, the official said. The details have become clearer now that the assault team has been debriefed, the official said, speaking on condition of anonymity because he was not authorized to speak on the record.

He said the raid should be described as a precision, floor-by-floor operation to hunt and find the al-Qaida leader and his protectors, rather than as it has been portrayed by a succession of Obama administration briefers since bin Laden's death was announced Sunday night.

In another development, aviation experts said a helicopter used in the assault appeared to be a stealthier, top secret and never-before-seen version of a routinely used special ops helicopter. The helicopter made a hard landing and was destroyed by the military team at the site, leaving behind wreckage for experts to analyze.

As the SEALs moved into bin Laden's compound, they were fired on by bin Laden's courier, Abu Ahmed al-Kuwaiti, who was in the guesthouse, the senior defense official said. The SEALs returned fire, and the courier was killed, along with a woman with him. She was hit in the crossfire, the official said.

The Americans were never fired on again as they encountered and killed a man on the first floor and then bin Laden's son on a staircase, before arriving at bin Laden's room. Officials have said bin Laden was killed after he appeared to be lunging for a weapon.

White House and Defense Department and CIA officials through the week have offered varying and foggy versions of the operation, though the dominant focus was on a firefight that officials said consumed most of the 40-minute assault:

- "There were many other people who were armed ... in the compound," White House spokesman Jay Carney said Tuesday when asked if bin Laden was armed. "We expected a great deal of resistance and were met with a great deal of resistance."

- "For most of the period there, there was a firefight," a senior defense official told Pentagon reporters in a briefing Monday.

- And though officials later revised these words, White House counterterrorism adviser John Brennan originally said bin Laden, too, took part in the shootout. Later the administration said bin Laden wasn't armed but that there were guns in the room.

NBC News, which was first to report that four of the five people killed were unarmed, said the majority of the operation was spent gathering up the compound's computers, hard drives, cellphones and other items that could provide valuable intelligence on al-Qaida and potential operations worldwide.

Those materials have been taken to the FBI lab at the Marine Corps base at Quantico, Va., the defense official said.

Widely published photos of the remains of the MH-60 Black Hawk helicopter that made a hard landing at the outset of the operation - and was destroyed with explosives before the SEALs left - show it had been modified to make it harder to detect with radar, said Richard Aboulafia, aviation expert with the Teal Group consultants said.

"It's pretty clear it was meant to penetrate Pakistani airspace," he said.

 The SEAL team was flown in by an elite Army Special Operations unit, known as the Knight Stalkers, according to a defense official, speaking on condition of anonymity to discuss the clandestine operation. The unit is based at Fort Campbell, Ky., and Obama is scheduled to visit there Friday.

The Knight Stalkers specialize in night flight operations and are equipped with Black Hawk, Chinook and MH-6 Little Bird helicopters. But Aboulafia said the existence of a helicopter like the one at the scene in Pakistan "was a very well-kept secret."

Also Thursday, two shopkeepers in Pakistani told The Associated Press that the bodies of al-Kuwaiti and his brother are shown in other photos taken in the compound after the raid.

The photos were published by Reuters news agency, which said it had bought them from a Pakistani security official who entered the compound after the assault.

The shopkeepers said they couldn't identify a third man's body in the photos. But by elimination, that would suggest the third man was bin Laden's son, since the Obama administration has said five were killed - bin Laden, his son, the courier, the courier's brother and a woman.

Prospects for ever seeing photos of bin Laden's corpse are uncertain now that President Barack Obama has decided not to release them publicly, said Scott Hodes, a former Freedom of Information and Privacy Act attorney at the Justice Department. The White House is exempt from FOIA, so the law wouldn't apply if the images are controlled there. The CIA, which had operational control of the mission, and the Defense Department can use a series of exemptions from the act to block release of the images.

The Associated Press on Monday requested through the FOIA photos of bin Laden's body as well as other materials, including video taken by military personnel during the raid and on the USS Carl Vinson, the ship that conducted bin Laden's burial in the North Arabian Sea. The government has 20 days to respond to a FOIA request.

The Obama administration has pledged to be the most transparent government in U.S. history and to comply much more closely with the Freedom of Information Act than the Bush administration did.

Ultimately, the issue could wind up in federal court.

"I think that it's going to be a hard road," Hodes said. "It's not inconceivable that a court is going to say to release them. But I think the government will fight because it's made its decision."

Sarah Palin, the 2008 vice presidential nominee and former Alaska governor, on Wednesday said Obama should stop "pussy-footing around" and release the photos of the slain bin Laden.

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