Police surrounding the home shot and killed the gunman after hours of failed negotiation attempts.
At 3 a.m., Aurora Police sent out emergency notifications for residents living near the 16000 block of East Ithaca Place. Several nearby homes were evacuated for safety reasons.
Aurora police have not released the names of anyone involved. However, multiple family members have identified two of the victims inside the home as Stacie Philbrook and her step-father, Anthony Ticali.
Philbrook's boyfriend is believed to be the third victim. Late Saturday evening, after some initial confusion, family members told 9NEWS that his name is Chris Ratliffe.
Family members also told 9NEWS Stephanie Philbrook Archuleta escaped from the home and told police officers that her husband, Sonny Archuleta, was still inside. She said he was armed and had fired shots inside the home.
Before jumping out of a second-story window, she saw the three "lifeless" bodies of her step-father, sister and her sister's boyfriend. Stephanie was not injured.
Authorities attempted to make contact with Sonny Archuleta. Hostage negotiators were called in and managed to speak to him on the phone.
Phone contact continued intermittently throughout the next several hours as negotiators told Archuleta to come out of the house. They tried speaking to him using a bullhorn outside as well. He did not comply with any of the requests.
Police say he was behaving "very irrationally" and often hung up on negotiators.
"The cops that were standing there [said] he was on methamphetamine," said neighbor Jennifer Williams.
"When the cops were trying to get Sonny out of the house, [said] they've known he's been up for four days," Williams said. "[Negotiators said] 'you know whatever's been done has been done, but come out so we can help you. '"
By 8 a.m., SWAT members moved in front of the town home to break out a window.
Upon seeing this, Archuleta allegedly fired multiple rounds. The bullets struck the SWAT vehicle but did not injure any officers.
"I'll be honest with you, I've never been so scared in my life," said neighbor Michael Ignace. "I've never had anything this close to me."
Teams deployed tear gas inside the house and gave more commands to the suspect.
Just before 9 a.m., the suspect appeared in a second-story window and began firing at officers again. That time officers returned fire and hit the suspect.
Authorities then entered the home and found the bodies of two men and one woman. The fourth body was found in an upstairs bedroom and was confirmed to be the suspect.
No officers were injured during the standoff.
The incident remains under investigation.
(KUSA-TV © 2013 Multimedia Holdings Corporation)