Off-duty Border Patrol agent Jonathan Morales and Oscar Stewart, an Iraq War Army veteran, helped stop a suspected gunman who had opened fire at the Chabad of Poway, CA, synagogue on Saturday in what authorities praised as an "act of courage."

One person died and three more were injured in the hate-fueled attack during Passover services.

Stewart, 51, was in the back of the room when the shots rang out, he told reporters. The veteran said his military training kicked in. "I ran to fire. That's what I did. I didn't plan it. I didn't think about it. It's just what I did," he said.

Stewart said he started yelling expletives at the gunman, who stopped shooting when he heard Stewart's voice and fled the synagogue to a nearby vehicle, reports USA Today .

"Stewart caught up to the vehicle as the suspect was about to drive away," the San Diego County Sheriff's Department said in a statement. Morales also followed.

Stewart said he began punching the shooter's window when Morales told him to get out of the way.

"He yelled, 'Clear back! I have a gun!'" Stewart said. Then, Morales began firing.

The off-duty agent hit the car, but the gunman drove away, police said. Authorities later arrested John T. Earnest, 19, along Interstate 15. A rifle was found in the front passenger seat, police said.