One sheriff's deputy was killed and four others shot after police responded to a call about a disturbance at an apartment complex in an affluent suburban county outside of Denver, authorities said.
The deputies responded to a call of shots fired at the Copper Canyon Apartment Homes in Douglas County, about 26km south of Denver, around 6am (local time), said Jason Blanchard, a spokesman for the sheriff's office. They also said two civilians have also been shot by the suspect.
A source in the sheriff's office told KKTV that the situation is "not looking good for us" as deputies were shot at.
The sheriff's office said that the suspect knew police were coming and began firing when they arrived.
A hospital where three people were taken for treatment says those people suffered noncritical injuries.
Littleton Adventist Hospital reported receiving four patients.
Residents in the vicinity were advised to stay inside and avoid exterior walls and windows. The shooting started at the apartment building, which is located near County Line Road between Colorado Boulevard and University Boulevard.
There was no immediate information on the condition of the deputies, the sheriff's office tweeted, saying "the scene remains active".