ARLINGTON, Va. --

There were no obvious signs of trouble when gunman John Patrick Bedell approached a Pentagon security checkpoint Thursday night. But Pentagon police officer Marvin Carraway had seen that facial expression before. It betrayed Bedell's intentions.

"It's hard to describe that look," Carraway said in an interview Monday. "It's a look you would know if you had been in combat."

Carraway was one of three officers who returned fire after Bedell began shooting at them. Carraway and another officer, Jeffery Amos, suffered minor injuries. The officers fatally wounded Bedell, who was described as having a history of mental illness by his family.

The shooting is still under investigation, but Pentagon police chief Richard Keevill has said the officers responded appropriately to the threat.

"The system definitely worked," said Terry Sutherland, spokesman for the Pentagon Force Protection Agency. "The bottom line is these guys did their jobs."

The three officers - Carraway, 44, of Clinton, Md.; Amos, 46, of Woodbridge; and Colin Richards, 29, of Alexandria, all described the experience in similar terms. They said time seemed to slow down, and their training kicked in.

"When the shooter started running, he looked like a big target. At that point, I felt like I couldn't miss," said Richards, who was next to Carraway when the shooting occurred, not far from the Pentagon Metro station. "My vision was, like, big. My hearing - I could hear everything."

Carraway was grazed in the leg when Bedell opened fire on him from what was essentially point-blank range. Amos, who was a short distance away, responded when he heard the gunshot, and he was struck by a bullet in the right shoulder. Neither was seriously injured.

Carraway acknowledged that he was in fortunate not to have been more seriously injured. More than good fortune, though, Carraway believes the officers' training is the primary reason they successfully stopped Bedell.

Carraway, a Marine Corps veteran who served in the first Persian Gulf War, said he had been shot at before. Recognizing the look on Bedell's face as a potential danger gave him moments to prepare. Bedell, who did not speak during the confrontation, opened fire first, but Carraway was able to quickly take cover and return fire.

"My training and my experience - that prevailed," he said.

The officers say they are well aware that the Pentagon is a potential target and that they are the first line of defense. Amos said he is glad that he and the other officers were able to prevent a situation like what occurred last year at Fort Hood, where Maj. Nidal Hasan is charged with 13 counts of murder following a shooting spree on the Army post.

"We couldn't let this guy get into the Pentagon, fearing that the same situation may occur," Amos said. "Our training kicked in, and that's what we're trained to do - stop the threat."

Bedell, 36, left behind a stream of anti-government rants and conspiracy theories involving the U.S. military. He was a graduate student in electrical engineering at San Jose State University.