Five deputies were shot, one fatally, after responding to a domestic disturbance call at an apartment complex south of Denver on Sunday morning, the Douglas County Sheriff's Office said.
Two civilians were also shot, but their condition is unknown. Authorities have not yet disclosed the condition of the other injured officers who were dispatched to the Copper Canyon Apartments, which is located in Highlands Ranch.
The suspected gunman was shot by officers and is believed to be dead, the sheriff's office said.
A SWAT team and bomb squad truck are also reportedly on the scene, where officers first arrived at 5:13 a.m. MST.
Four people were taken to Littleton Adventist Hospital in relation to the shooting ― including the officer who died, officials said ― and three were taken to Sky Ridge Medical Center in non-critical condition, KUSA reported.
Vira Cober, 50, was still sleeping when her fiance called around 6:30 a.m. and told her to stay inside because of an active shooter in their apartment complex.
"About five minutes later, I heard a bunch of gunshots," Cober told HuffPost. "I'm in shock. Highlands Ranch is one of the safest places in the Denver metro area."
Steven Silknitter, Cober's fiance, had been working about 30 minutes away when he first heard about the shooting in Copper Canyon Apartments. He immediately headed home, frantically calling Cober to let her know what was happening. He was about a mile away from the complex when police stopped him from driving any further.
"I could hear 15 to 20 gunshots after I got off the phone with her," Silknitter told HuffPost. "It was just unbelievable ... Next thing I know, there's probably 20 or 30 different police cars, fire trucks, ambulances just all over the place."
This is the second mass shooting in five years to hit close to home for Silknitter. He lived in Aurora during the 2012 movie theater shooting.
"I'm just kind of at a loss for words," he said. "It's like, where do you go from here? Where do you move that you don't have to worry about getting shot?"
A reporter for a local Denver news outlet also said she heard gunfire as she arrived. Authorities are asking people to avoid the area.
The sheriff's office has a Fallen Officer Fund to provide assistance for its members who are seriously injured or killed in the line of duty.
A representative for the Copper Canyon Apartments did not immediately respond to request for comment.
This is a developing story. Please check back for updates.