Two people were killed, six others were were injured and a helicopter was struck after at least one gunman armed with a high-powered rifle began "shooting randomly" in Houston on Sunday, police said.
One suspect and one bystander were among the dead.
Four people and two constables were also injured, interim Houston Police Chief Martha Montalvo said, adding that both officers were released from the hospital. One suffered a wounded hand; the other was shot in a bullet-proof vest.
Authorities described a chaotic scene: A gas pump was struck during the shooting erupted in flames, and a helicopter helping to secure the area was hit with five bullets, police said.
A bomb squad was called to the area to detonate a suspicious item, officials told NBC News, and cars in the area, including two police cruisers, were shot. Photos released by the police department showed one vehicle with at least a dozen bullet holes in the windshield and the hood.
Authorities initially said there were two suspects, neither of whom were identified. One was injured during the shooting and hospitalized. The second man was pronounced dead at the scene; Houston police spokesman John Cannon described him as "the main active shooter" and said he was armed with a pistol and an "AR-15-type weapon."
At a briefing Sunday afternoon, Cannon said it was unclear whether the two men knew each other — or whether it was accurate to describe the injured man as a suspect.
"We don't know what his role was yet," Cannon said, adding that the man was providing police with "his version of what was happening out here."
The gunfire began at an auto detail shop in West Houston just after 11 a.m. (noon ET), Cannon said, when a customer, a man in his 50s, had just arrived at the shop.
The man "parked his car to get it detailed, and in a minute or two, the suspect came out and shot him for no apparent reason," Cannon said.
The man was pronounced dead.
The three additional wounded victims were adults who did not appear to have life-threatening injuries, Cannon said. One of them, Byron Wilson, was shot in both legs and a shoulder, his mother told NBC News. Another, Denise Slaughter, was on her way to brunch when she heard shots.
The motive remained unclear. Earlier Sunday, Montalvo said that "everything is open at this time."