Houston police officer John Calhoun didn't have any choice about wearing his protective vest when he was sent to investigate a call about a suspicious person.

HPD officials told the Houston Chronicle that departmental requirement just might have saved his life.

Calhoun was shot about 2:30 p.m. Wednesday while struggling with an armed man near a bus stop along the 11900 block of Airline Drive in north Houston.

The round struck Calhoun in the side but never penetrated his body armor.

"He's lucky to be alive," said John Cannon, a Houston police spokesman.

Even after he was shot, Calhoun was able to draw his own pistol and return fire. The other man was struck and later died at Houston Northwest Medical Center, police said.

Calhoun, 28, was taken to Memorial Hermann Hospital at the Texas Medical Center. "He's got very deep bruising, and he says he's very sore," Cannon said.