Details of Fort Hood Battle Between Maj. Hasan, Cops Still Murky

More details are being released about the gun battle between Maj. Nidal Malik Hasan and the civilian police officers credited with stopping the Fort Hood massacre, but how exactly the alleged shooter was taken down remains murky.

Sgt. Mark Todd told "Good Morning America" today that it was bystanders who pointed him and Sgt. Kimberly Munley in Hasan's direction as they responded to calls of shots being fired at Fort Hood last week.

VIDEO: Background check on Maj. Malik Hasan wasnt shared with terrorism officials.Play

"When we first approached the scene there was a slight incline we had to go up," Todd said. "She broke to the right and I broke to the left and we both took cover."

"I gave him commands, 'halt, drop your weapon,' and he fired on me," Todd said.

While Munley has been hailed as the hero by Fort Hood authorities, her shots bringing down Hasan even though she had been shot three times herself, a report today in the New York Times suggests it was Todd who got off the shots that felled the alleged shooter.

The Times quoted an unidentified witness who said Hasan shot Munley immediately and while she was on the ground, Todd rounded a corner and shot Hasan while the gunman had paused to put another magazine in the pistol.

VIDEO: Foot Hood Hero Sgt. Mark Todd on the ExperiencePlay

Todd was careful to avoid specifics today on "Good Morning America" and said he could not comment on anything Hasan had said during the exchange.

It was the first time in 25 years, he said, that he's had to use his gun.

"There was really no time to think," he said. "We just relied on our training."

Once Hasan's gun had been secured, Todd said they immediately began life-saving measures on him.

"We can't just sit there and watch him die," he said. "We have to do everything we can to preserve life."

Hasan remains hospitalized at Brooke Army Medical Center in San Antonio where he is reportedly paralyzed.

Munley told Oprah Winfrey Wednesday that she was taking her time to recover.

"Every day is a progress for me, and things are getting better day by day," she said on Winfrey's talk show. "Emotionally, I'm just hoping that the rest of the officers and the injured and the families of the deceased are healing as well."

Experts Say Information About Hasan's Gun Purchase Was Critical

Investigators have continued to probe all aspects of the shooting. A look into Hasan's modest apartment showed that most everything had been cleaned out, save for a few personal items including a book titled "Dreams and Interpretations."

Sources have told ABC News that in August 2009, Hasan walked into the Guns Galore gun store in Killeen, Texas, and legally purchased the FN Herstal tactical pistol that authorities believe was used in the Fort Hood shooting.

An FBI background check under the National Instant Background Check System was done when Hasan purchased the pistol -- but that information was never shared with the Joint Terrorism Task Force in Washington, which was aware that Hasan had repeatedly contacted a radical imam suspected of having ties to al Qaeda.

The FBI's Joint Terrorism Task Force ran down intelligence leads relating to Hasan late last year but closed the inquiry sometime in early 2009.

"The piece of information about the gun could have been critical," said former FBI Special Agent Brad Garrett. "One of the problems is that the law sometimes restricts you in what you can do."

As investigators continue to examine whether there were missed signals in the Fort Hood shooting massacre, some individuals are frustrated that there are still gaps in information-sharing, especially when it comes to looking at federal gun laws.

The Fort Hood shooting followed a June incident in Little Rock, Ark., where police say Abdulhakim Mujahid Muhammad opened fire at an Army recruiting station, killing a soldier. Muhammad was under FBI investigation for possible ties to terror and travel to Yemen.

A senior law enforcement official tells ABC News that Muhammad purchased a gun in the weeks before the shooting at a department store. An FBI background check was done -- but the FBI counterterrorism investigators working Muhammad's case were apparently unaware.

Federal Law Does Not Prohibit Suspected Terrorists From Buying Guns

Senior law enforcement officials say the Brady Law forbids them from widely sharing information about legal gun purchases.

"We need to be smarter about sharing information," said former 9/11 commissioner Richard Ben-Veniste. "It's very disturbing to see…that the FBI is precluded from sharing information."

Current federal law does not prohibit people on the terrorist watch lists from purchasing guns unless there is a prohibiting factor, such as being a fugitive, having a felony conviction or charge, renouncing U.S. citizenship or having been determined as mentally impaired.

Earlier this year, Sen. Frank R. Lautenberg, D-N.J., introduced legislation which would prevent known or suspected terror suspects from purchasing firearms.

"If someone on any terrorist watch list tries to buy a weapon, law enforcement must be informed – period," Lautenberg said in a statement Wednesday when contacted by ABC News. "If some people are being blocked from flying on an airplane, then we should certainly know when they are buying an assault weapon."

The FBI unit responsible for background checks on gun purchases does provide leads to the FBI about some high priority terrorism suspects; but that watch list is not inclusive of everyone the government may have concerns about.

FBI Director Robert S. Mueller III, at a June 4, 2009, Senate appropriations hearing, said on the issue, "We are notified when there is a -- appears to be a purchase of somebody who is affiliated with a terrorist group. But that is different than barring that individual from the outset from purchasing a weapon. But again, I have to defer to the Department of Justice in terms of the policy position that it is going to take on that issue."

In a statement, NRA spokesman Andrew Arulanandam said, "It isn't surprising that, while the investigation is still ongoing and before all the facts are known, Sen. Lautenberg and the gun control lobby have rushed to exploit this sorrowful event."