One after the other, gun shots became the community alarm at the Copper Canyon Apartments in Highlands Ranch.
"For a quick second, I thought it was fireworks," said Heath Pence, who looked outside her window and saw a SWAT member on her neighbor's roof.
She later realized she was one building away from where the shots were coming from.
"I'm a little bit shaken up," she said. "It's just a crazy day."
It wasn't the gun shots that woke Jani Stern. Around 6:30 a.m., she heard someone walking on her roof and thought it an odd time for roofers to be working.
But the boots were from the SWAT Officers. They knocked on her door before sunrise.
"It was quite a way to start the last day of the end of the year, to have SWAT team members in your face," said Stern.
The shots began just after 5 a.m. and lasted until after 7:30 a.m.
The Douglas County Sheriff's office sent out a message on Twitter telling residents to stay away from windows and walls.
They got the all clear just after 9:30 a.m.
"I've had a lot of emotions going through today," said Pence. "Anger, frustration, sadness for the police officers and the two victims that got shot today too."
The two injured civilians have not yet been named, but they are believed to be other residents in the building who were not involved with the suspect.