Police in Colorado Springs are working Monday to determine a motive after a gunman walked into a birthday party inside a mobile home over the weekend and opened fire, killing six people and then himself.
Investigators described the suspect as a "boyfriend of one of the female victims," while the children inside the trailer at the time – who were uninjured -- are now with relatives, according to Colorado Springs Police.
"My vow to this community and to the families who have lost someone today is that this department will do everything we can to find you the answers you deserve and to be here for you with an unwavering support," Vince Niski, the department’s chief, said in a statement.
The names of the gunman and the victims have not been officially released. Officers that responded to the scene at Canterbury Park shortly after midnight Sunday found six deceased adults and one with serious injuries, police say. The injured male adult later died at a local hospital.
Police say the suspect "drove to the residence, walked inside and began shooting people at the party before taking his own life," adding that "friends, family, and children were gathered inside the trailer to celebrate when the shooting occurred."
Freddy Marquez, one of the partygoers who left early because his wife had work in the morning, told the Denver Post that the guests were all members of the same family. He said his wife lost her mother and two brothers in the shooting.
One of the witnesses said they knew the gunman and described him as "quiet" and "serious," according to the Colorado Springs Gazette.
Police say the names of the suspect and victims will be released after a coroner has confirmed their identities and cause of death.
The attack was Colorado’s worst mass shooting since a gunman killed 10 people at a Boulder supermarket March 22.
"The tragic shooting in Colorado Springs is devastating," Gov. Jared Polis said Sunday, "especially as many of us are spending the day celebrating the women in our lives who have made us the people we are today."
Anyone with information related to the shooting is asked to call the Colorado Springs Police Department at (719) 444-7000. Anonymous tips can also be given to the Crime Stoppers Tip Line at (719) 634-STOP (7867) or 1-800-222-8477.
The Associated Press contributed to this report.