Police believe the suspect was the boyfriend of one of the victims, who shot six people and then himself in Colorado Springs after midnight on Sunday.
Chief Vince Niski said the Colorado Springs Police Department has a "moral obligation" to bring justice to the victims and their families at a press conference on Tuesday.
In the homicide investigation "initiated on Sunday" that is still ongoing, police revealed the suspect's name.
"I want to make it clear that we will only be using the suspect's name once, that that person will only be referred to as 'the suspect' throughout the synopsis as to not to give their actions any notoriety," violent crimes chief said.
"Two families gathered together at a residence" on Saturday "to celebrate the birthday of their family members," who are related through the marriage of Melvin Perez and Mayra Ibarra Perez, "who were both present, along with their children."
"Among the many attendees were Mayra's siblings, Jose and Sandra Ibarra," and they gathered at Melvin's mother's, Joana Cruz, and stepfather's home. Cruz had her two children there at the party as well, identified as Jose Guttierez.
"When the suspect arrived, there were 10 family members present at residence, seven adults and three children, ages 2, 5, and 11."
"We have recovered evidence showing that the suspect arrived at the residence alone, the suspect entered the residence and shot all six victims in quick succession," he said. "The suspect then shot himself shortly thereafter."
The Colorado Springs Police received three 911 calls, one of which "originated from a phone inside of the residence and captured sounds of rapid gunfire."
"One adult family member was able to escape the residence unharmed as the shooting was occuring, the three children remained inside the residence during the occurrence and were also unharmed."
"The evidence supports were in close proximity to the shooting event and witnessed what happened," he said, adding the adult who escaped placed the third 911 call.
Three teens who had left the residence to retrieve something were fortunately spared from the horrific shooting, but returned to the house to find the bloodbath that occurred.
"They attempted to render aid and provide shelter to the children," he said.
Arriving officers quickly removed the children from the residence and were able to retrieve members who were also unharmed. They found only one victim still breathing but "gravely wounded," which was Jose Gutierrez Cruz.
"They received information from this victim that the suspect was still inside," he said, but police didn't know if he was still alive, forcing them to do a sweep of the residence while retrieving any other unharmed victims from the residence.
After the suspect was found to be dead, Gutierrez was transported to a hospital but succumbed to his injuries. Medical personel then arrived to the residence to find other slain victims.
"The suspect was identified as 28-year-old Teodoro Macias Jr of Colorado Springs. The suspect had been dating one of the victims, Sandra Ibarra, for approximately one year."
"The suspect was not invited to the family gathering and evidence supports he became upset over that lack of an invitation."
Macias had a history of abusive and manipulative behavior towards Sandra and would "isolate her from her family" and "make efforts to avoid her from attending family gatherings."
There are no reported domestic violence incidences between Sandra and Macias, who does not have a criminal history.
"A firearm was recovered under the suspect." It was a Smith and Wesson M&P 9mm and purchased empty from a dealer.
Authorities responded to the shooting at Canterbury Mobile Home Park yesterday where the horrific gun rampage left residents and children traumatized.
Nubia Marquez said her two brothers were killed in the shooting: Melvin Perez, 30, and Jose Guttierez, 21.
Ms Marquez said her mom Joana Cruz, 53, was also killed, as well as Mr Perez's wife Mayra, 32, Mayra's sister Sandra Ibarra and brother Jose Ibarra.
Nubia and her husband Freddy said the killer was Sandra's boyfriend, who has since been identified as Macias.
A group of friends, family and kids were gathered inside a trailer home for a birthday party when the tragedy took place.
Nubia told the Gazette that Sandra's boyfriend - known to them as "Junior" - often carried a gun and had a "serious" and "quiet" personality.
When Nubia and Freddy left the party at 10pm, they said "everybody was calm".
Nubia said: "My mom had always liked celebrating them together."
"They were all great people," Freddy said.
Colorado Springs police said in a statement: "The suspect, a boyfriend of one of the female victims, drove to the residence, walked inside and began shooting people at the party before taking his own life," .
By the time officers arrived, six people were dead and the shooter was critically injured after shooting himself.
WHAT WE KNOW SO FAR
He was transported to the hospital and later died, authorities told the Washington Post.
Yenifer Reyes, a resident of the mobile home neighborhood, said she awoke to the sound of gunshots.
“I thought it was a thunderstorm,” she told the Denver Post. “Then I started hearing sirens.”
Reyes said she watched police escort the children out of the home as they cried "hysterically."
They are all unharmed and currently with other relatives, police said.
"From the officers who responded to the shooting to the investigators still on scene, we are all left incredibly shaken," Colorado Springs Police Chief Vince Niski said.
"This is something you hope never happens in your own community, in the place that you call home."
A motive has not yet been determined.
The El Paso County Coroner's Office is expected to officially release the identities of the victims at a later date after notifying the families of those who died.
Colorado Springs Mayor John Suthers asked for patience as officials investigate the nature of the crime and provide answers to the families involved.
"Today we find ourselves mourning the loss of lives and praying solemnly for those who were injured and those who lost family members in a senseless act of violence on Sunday morning," Suthers said.
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Colorado's Governor Jared Polis echoed the statement.
“The tragic shooting in Colorado Springs is devastating, especially as many of us are spending the day celebrating the women in our lives who have made us the people we are today," he said.
This shooting comes just over a month after a man in Boulder killed ten people in a grocery store with an AR-15 style weapon