(NEXSTAR) — Two young children have died, and over a dozen others are injured following a gunman shooting through the windows of a church at Annunciation Catholic School in Minneapolis during a Wednesday morning Mass, the police revealed during a press conference. The suspect shooter is also deceased.

Minneapolis Police Chief Brian O’Hara reported that calls of a shooting at Annunciation Catholic Church, located on the city’s southern side, were received shortly before 8:30 a.m. CT.

O’Hara stated that two children, aged 8 and 10, were killed while seated in the pews. Seventeen additional church attendees sustained injuries, including 14 children and three adults in their 80s, who were present for the Mass.

Children’s Minnesota, a pediatric trauma hospital, indicated that seven children, aged 9 to 16, were admitted for treatment. Hennepin Healthcare, which features Minnesota’s largest emergency department, reported treating both adults and children, aged 6 to 14. Seven are considered critically injured.

The shooter, identified as 23-year-old Robin Westman, had no previous criminal record. Westman was found armed with a rifle, shotgun, and pistol, as stated by O’Hara. The weapons were used to open fire from outside, through Annunciation Church’s windows, during a morning Mass attended by students and parishioners.

O’Hara said it is believed that the shooter used all three weapons during the shooting, which he also described as “deliberate.”

“This was a calculated and violent act against innocent children and other worshippers. The unimaginable cowardice and cruelty of firing into a church filled with children is beyond comprehension,” remarked the police chief, who also pointed out that some church doors were barricaded with wooden planks from the outside.

He said the shooter was found dead in the rear of the church of what appears to be self-inflicted gunshot wounds.

Authorities have not yet disclosed whether the shooter had any connection to Annunciation. The shooter posted a “manifesto” on YouTube in time with the shooting, O’Hara said. The video has been taken down and is being reviewed by investigators.

Shortly after 10 a.m. CT, students and families could be seen walking away from the school. Many were trickling out of the school with adults, giving lingering hugs and wiping away tears.

O’Hara said “dozens” of children were inside the church at the time of the shooting. The first day of school was on Monday, and an all-school Mass was scheduled at 8:15 a.m. Wednesday morning, according to its website.

Bill Bienemann, who lives near the church, told The Associated Press, he heard “sporadic” gunfire that went on for “several minutes.” Bienemann’s daughter, Alexandra, attended Annunciation School for nine years.

“It breaks my heart. It makes me sick to my stomach knowing that there’s probably people that I know that are either injured or maybe they were even killed,” she told The Associated Press. “It doesn’t make me feel safe at all in this community that I’ve been a part of for so long.”

Aubrey Pannhoff, a 16-year-old student at a different Catholic school, stood crying just outside the police cordon. She had rushed to Annunciation after her own school’s lockdown and prayer service, and she said she was asking God: “Why?”

“It’s little kids,” she said. “It’s just really hard for me to take in.”

“Don’t just say this is about thoughts and prayers right now,” Minneapolis Mayor Jacob Frey said at the news conference with the police chief. “These kids were literally praying. It was the first week of school. They were in a church.”

Gov. Tim Walz said on social media that he had been briefed on a shooting at Annunciation Catholic School, located on the city’s south side, calling it “a horrific act of violence.”

On Truth Social, President Donald Trump said he was briefed on the “tragic shooting” and that the White House would continue to monitor it. Trump signed a proclamation Wednesday afternoon ordering flags to be lowered at all government buildings until sunset on Sunday “as a mark of respect for the victims of the senseless acts of violence.”

The Associated Press contributed to this report.