Six people are dead after a gunman entered a birthday party and began shooting inside a mobile home in Colorado Springs before killing himself during the early-morning hours of Mother’s Day, police announced Sunday.

The mass shooting unfolded around midnight Sunday at the Canterbury Mobile Home Park, about eight miles outside downtown Colorado Springs, police said. The gunman, who authorities said was the boyfriend of one of the female victims, has not been publicly identified.

The Colorado Springs Police Department said in a news release that the man “drove to the residence, walked inside and began shooting people at the party before taking his own life.” The shooter’s motive is still being investigated, police said, and the type of firearm used was not specified.

All of the victims, whose names and ages have yet to be released, were adults. One of the victims was the one celebrating a birthday, police said. None of the children at the party were injured, authorities said. The children are now with relatives.

When police arrived at the scene at 12:18 a.m. Sunday, they said they found the male shooter, an adult, who was transported to a hospital with “serious injuries.” Authorities confirmed that he died at the hospital.

The Mother’s Day mass shooting in Colorado’s second-biggest city was the latest in a grim litany of rampages that have rocked places like Atlanta and Indianapolis this spring. The shooting comes less than two months after the state was rocked by a gun attack at a King Soopers supermarket in Boulder that left 10 dead.

Sunday’s massacre is believed to be at least the seventh public mass shooting since March, according to a Washington Post database.

The El Paso County Coroner’s Office will be releasing the names of the Colorado Springs victims “at a later date,” police said. Authorities promised to “respectfully notify” family members of the victims before their names were made public.

Gov. Jared Polis (D) on Sunday said he mourned with the victims’ families.

“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 in a statement.

Colorado Springs Mayor John Suthers (R) vowed there would be a “thorough investigation” and asked for the public’s patience as law enforcement seeks answers. Like Polis, he said he was grieving with those lost at the birthday party.

“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,” the mayor said in a news release.

Colorado Springs Police Chief Vince Niski said in a statement that the authorities who responded were “all left incredibly shaken” by what they saw at the mobile home.

“Words fall short to describe the tragedy that took place this morning,” he said. “This is something you hope never happens in your own community, in the place that you call home.”

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