The unidentified suspect was seen standing in the middle of the street, holding a long gun, and fired at propane tanks laced with gunpowder when police approached him.
“Officers responded to the scene and approached what they thought was a possible suspect," said Denver Police Chief Richard White. "As they were approaching the suspect fired one shot at what looked like a makeshift incendiary device which was activated."
Police said the gunman called the police himself, hoping to get involved in a shootout.
After the suspect blew up one of the propane tanks, police shot him in the chest, sending him to the hospital in critical condition.
No one was injured when one tank exploded. The other did not detonate.
“There are several potential incendiary devices in the area," White said. "We evacuated the area to make sure no one was in harm’s way and the bomb squad is actively trying to mitigate those devices."
One woman was found dead and another was shot in the leg.
Denver police tweeted at 11:16 a.m. local time the shooter was "down," then searched the area for other explosives.