Officials in Colorado believe the gunman who killed six people at a birthday party over the weekend was irritated that he had not been invited.
Teodoro Macias, 28, is accused of fatally shooting his girlfriend Sandra Ibarra-Perez, 28, and five relatives before turning the trigger on himself.
The assault occurred early Sunday at the Canterbury Mobile Home Park in Colorado Springs.
The celebration was for three friends, two of whom had died.
The attack came less than two months after a mass shooting that left 11 dead at a grocery store in the north-central Colorado city of Boulder.
Police say the Colorado Springs gunman had a “conflict” with the targeted family at a separate event about a week earlier, and was a jealous boyfriend.
“At the corner of this horrendous act is domestic violence,” the Colorado Springs Police Chief Vince Niski told a news conference on Tuesday.
He added: “When he [Macias] wasn’t invited to a family gathering, the suspect responded by opening fire.”
He said the killer had “displayed power and control issues”, and had been in a relationship with his girlfriend for about a year. He had no criminal record.
Three teenagers left the party to get an item from a neighbour shortly before the shooting unfolded and returned to the trailer after the attack, police Lt Joe Frabbiele told a news conference.
Three children, aged two, five and 11, witnessed the shooting, and were not physically harmed, said police. Seventeen bullet casings were found in the mobile home.
On Tuesday, Colorado Springs police identified the other victims:
- Melvin Perez, 30
- Joana Cruz, 53 (Melvin’s mother)
- Jose Gutierrez Cruz, 21 (Melvin’s brother)
- Mayra Perez, 32 (Melvin’s wife)
- Jose Ibarra (Mayra’s brother)
Nubia Marquez, Melvin Perez’s sister and Joana Cruz’s daughter, told the Colorado Springs Gazette that the three had the same birthday week and “had always liked celebrating them together”
She and her partner, Freddy Marquez, attended the party at the Cruz family trailer park home.
The couple, however, told reporters that they left around 22:00 local time on Saturday night.
The shooting occurred just after midnight on Mother’s Day, in the early morning hours.
Mr Marquez paid tribute to his mother-in-law, telling the Gazette that Mrs Cruz was a “loving” and “hard-working” mother of four who was “always laughing” and had raised her children to be “great people”.
According to Mr Marquez, the gunman was a “quiet” and “serious” man who always kept a pistol with him.
According to investigators, the intruder did not have a lawful right to the semi-automatic weapon.
Colorado Governor Jared Polis issued a statement on Sunday condemning the “terrible act of violence” adding that it occurred on a day when “many of us are spending the day celebrating the women in our lives who have made us the people we are today”