This story was updated at 8:45 p.m. ET.

Police in Houston killed a gunman on Sunday in a chaotic shootout that left one other person dead, six wounded — including two officers — and set off a fire at a nearby gas station when bullets struck a gas pump, authorities said.

Witnesses reported that a gunman approached a man who had just pulled up to an auto detail shop and opened fire with a pistol, police spokesman John Cannon said.

"It appears that it was a random, unprovoked attack," Cannon said. The victim, a male in his 50s, died, he said.

The gunman fired on the first officer to respond to the scene, riddling his car with bullets, including many that struck the windshield, Cannon said. At least five shots also struck a police helicopter, he said.

The officer escaped injury and called for help. A shootout ensued with arriving officers before a SWAT team member shot the suspect dead at about 11:10 a.m., about an hour after police arrived at the scene, Cannon said. Two constables were wounded, not seriously, one struck in the hand and other in his bulletproof chest vest, he said.

A second person, still considered a possible suspect, was also shot, possibly by the primary shooter, Cannon said. He was interviewed at the hospital to give police his version of what happened, Cannon said.

Three other people, believed to be innocent victims, were also wounded but not seriously, officials said.

Bullets from the shootout struck a gas pump at a station next to the detail shop, triggering a fire that left the station building charred, Cannon said.

Police do not know the motives behind the shootings and are seeking the public’s help.

“We are trying to piece all of this together,” acting Houston Police Chief Martha Montalvo said. “It’s still a very ongoing investigation.”

The gunman had both a pistol and a rifle, police said.

"Obviously they had a high-powered rifle," Montalvo said. "We believe one of them had an AR-15.”

The shooting occurred in west Houston, adjacent to a residential area, just east of the Sam Houston Tollway, a major highway dissecting the Texas city.