ATLANTA -- A former Marine cook was acting in fear of his life and will not face charges for fatally stabbing one teenager and wounding a second while fending off a robbery in Midtown Atlanta by a group of youths armed with two guns and a pair of brass knuckles.

Police spokeswoman Sylvia Abernathy says 36-year-old Thomas Autry acted in self-defense when the suspects jumped him Monday night and he struck back with a pocket knife he had.

The girl he stabbed, 17-year-old Amy Martin, was pronounced dead at a nearby hospital. The accomplice who was wounded, 17-year-old Christopher Daniel, was listed in critical condition at Atlanta Medical Center yesterday afternoon.

Daniel and three other youths involved in the robbery, a 16-year-old and 17-year-olds Kendall Barksdale and Christopher Hayes, were charged with aggravated assault and armed robbery.

The day after the attack, Autry returned to his girlfriend's apartment, where he had the locks changed. He told Channel 2 Action News he doesn't feel like a hero.

"I was just trying to protect myself. I'm sorry," he said.

Autry, who was stationed in Saudi Arabia during the first Gulf War, says he tried to flee his attackers but they caught him and one of them pointed a gun at him.

Autry began running down the street yelling for help. Residents who heard him called 911. While he was running, Autry pulled a pocket knife from his backpack.

Two of the robbers jumped from the car. When one of the robbers pointed a shotgun at him, the Autry kicked it out of his hands.

At that point two of the robbers jumped on the victim. During the struggle he stabbed both Martin and Daniel. Martin died of her wounds.

Her mother, Alesher Zeigler, says, "She was trying to fit in... and this new boyfriend she was with he just totally changed her, totally changed her."

Contrary to earlier reports an autopsy showed that Martin was not pregnant when she was killed.