Four Detroit police officers, including a commander, were shot Sunday afternoon inside a station in the department's Northwest District.
The gunman who opened fire was killed when officers returned fire, police said.
The station, which services the 6th precinct, is near Plymouth and Warwick roads.
Commander Brian Davis suffered the most serious injuries, police said. He was taken to Sinai-Grace Hospital where he was in critical condition.
Police said Officer David Anderson, Sgt. Ray Saati and Sgt. Carrie Shultz were the others shot. They were all taken to Sinai-Grace Hospital, treated and have been released.
Police said Saati was grazed by a bullet to his face, and Shultz was shot in her vest, which stopped the bullet.
"(The gunman) walked in, and indiscriminately began firing," Police Chief Ralph Godbee said during a news conference Sunday night. "As you can imagine, utter chaos and pandemonium took place."
Godbee said officers returned fire and took cover.
"We're very relieved that it appears that all of our officers are going to be OK," Godbee said. "Of course, we have to take a step back and reassess security procedures at each one of our facilities."
Godbee said police are investigating the shooting, and more information on what happened should be available on Monday.