It was not clear how many people checked into the shelter.
A Code Red alert has been issued by the sheriff's department, warning citizens to stay indoors as the shooter is believed to still be at large. In all, five deputies were shot.
Douglas County Sheriff Joe Pelle's son, Jeff, was among those who were injured in the incident.
One deputy was confirmed dead and the six others were taken to hospitals, the sheriff's office said.
An emergency call came in just after 6:30 a.m. about a domestic violence incident at Copper Canyon Apartments.
Excessive video gaming to be named mental health disorder
It also lists conditions medical personnel can use to decide if a gamer's behaviour can be described as a mental health disorder. World Health Organization has been working with the 10 International Classification of Diseases (ICD) since 1990.
Two civilian residents of the complex were shot by the gunman and have non-life threatening injuries, Sheriff Tony Spurlock reported at a presser. The exact number of casualties is not yet known.
Police in a Colorado city just outside of Denver said "multiple deputies" are down after being shot while responding to a disturbance call early Sunday.
A SWAT team responded to the scene, according to a spokeswoman for the Sheriff's office, and a major highway south of the city was shut down.
Law enforcement agencies including the Parker Police Department, the Lone Tree Police Department, the Castle Rock Police Department and the Colorado State Patrol were lending assistance.