Story highlights Police: A gunman armed with a pistol and an AR-15 shot at random

It's unclear whether another armed man in police custody is a suspect

A gunman fired on a police helicopter and a fire broke out at a nearby gas station

(CNN) Two people died, including a suspect, after at least one gunman armed with a high-powered rifle opened fire Sunday in Houston, aiming at bystanders, police patrol vehicles and a helicopter.

The slain victim was a man shot in the head inside his vehicle, acting Houston Police Chief Martha Montalvo told reporters. A suspect also was killed, police said.

A second armed man suffered gunshot wounds and was taken into police custody. Police originally described him as a suspect, but later said they weren't sure.

"He's telling us a version as to what his involvement is," Houston Police spokesman John Cannon said. "We need to verify that before we say anything publicly."

A motive for the shooting wasn't immediately clear.

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