KILLEEN, Texas — Sgt. Kimberly D. Munley has been applauded as a hero across the nation for shooting down Maj. Nidal Malik Hasan during the bloody rampage at Fort Hood last week. The account of heroism, given by the authorities, attracted the attention of newspapers, the networks and television talk shows.

But the story of how the petite police officer and the accused gunman went down in an exchange of gunfire does not agree with the account of an eyewitness.

The witness, who asked not to be identified because it could damage his military career, has been interviewed by the Defense Criminal Investigative Division. He said Hasan wheeled on Munley as she rounded the corner of a building and shot her, putting her on the ground. Then Hasan turned his back on her and started putting another magazine into his semiautomatic pistol.

It was at that moment that Senior Sgt. Mark Todd, 42, a veteran police officer, rounded another corner of the building, found Hasan fumbling with his weapon and shot him.

How the authorities came to issue the original version of the story, which made Munley, 35, a national hero for several days and obscured Todd's role, remains unclear.

Lt. Col. Lee Packnett of the Army's Office of the Chief of Public Affairs at the Pentagon declined to say whether it was Todd who had shot Hasan. "It could have been, but the final outcome will be determined by the results of the ballistics tests."

Todd's wife, Lisa, said he had asked the Army to protect his identity in the immediate aftermath of the shootings. Her husband did not consider himself to be the real hero of the day, she said. "They were in this together," she said.

Neither Todd nor Munley, 35, were made available by the military for this article. They did appear on the "Oprah Winfrey Show," and offer their first public comments on the shooting.

Both are members of the civilian police force at Fort Hood. Todd said he and Munley had arrived at the Soldier Readiness Processing Center in separate squad vehicles about the same time.

Todd said that he had fired at the suspect, kicked his weapon away and placed him in handcuffs.

It was the first time in his 25 years in law enforcement and the military, Todd said, that he had used his weapon. "I just relied back on my training," Todd said.

The confusion over what happened and the quickness of the military to label someone a hero seemed reminiscent of the case of Pfc. Jessica Lynch in 2003, when the Army initially reported Lynch had been captured in Iraq after a Rambo-like performance in which she emptied her weapon and was wounded in battle. It was later learned she had been badly hurt in a vehicle accident during an ambush and was being well cared for by the Iraqis.

On Friday, the day after the Fort Hood shooting, Chuck Medley, director of emergency services at the post, said Munley had encountered Hasan, pistol in hand, chasing down a bleeding soldier. It was 1:27 p.m. She fired at him, he turned, they rushed at each other firing and both fell.

"He turned and charged her rapidly firing, and she did what she was trained to do," Medley said that day. He added, "She is absolutely a hero."

Several hours later, at a late-night news conference on the post, an official said Todd had arrived at the scene in the middle of the gunfight and had also fired his weapon.

The eyewitness, however, offered a different account. He said he was walking in a roadway between the main building, known as the Sportsdome, and five smaller buildings, on his way to be processed for deployment. Hasan was headed toward the main building, the witness said, when Munley came around the corner of a smaller building.

Hasan wheeled on her and shot her several times, the witness said. It was unclear whether she squeezed off a shot or not, but she fell over backward, disabled with wounds in her legs and one of her wrists, the witness said.

Hasan then turned his back on her and began to shove another magazine into his pistol. He did not appear wounded, the witness said. A few seconds later, Todd came around another corner of the same building. He raised his weapon and fired several times at Hasan, who pitched over backward and stopped moving.

"He shot her, turned away from her and was reloading, when he was shot," said the witness.