(NEXSTAR) — Two young children are dead and more than a dozen others are injured after a gunman fired shots through the windows of a Minneapolis Catholic church during a Wednesday morning Mass, police said during a press conference. The suspected shooter is dead.

Minneapolis Police Chief Brian O’Hara said calls came in shortly before 8:30 a.m. CT of a shooting at Annunciation Catholic Church, located on the city’s south side.

Two children, ages 8 and 10, were killed in the pews they were sitting in, O’Hara said. An additional 17 people sitting in the church were injured. The hospitals treating the victims said that 15 of the injured are children as young as 6 years old.

Children’s Minnesota, a pediatric trauma hospital, said seven children between the ages of 9 and 16 were admitted for care. Hennepin Healthcare, which has Minnesota’s largest emergency department, said it was caring for two adults and eight children between 6 and 14 years old. Seven were considered to be in critical condition.

Authorities helped to locate children that had been hiding in the school, O’Hara said, though the shooting appears to have been limited to the church. Classes began Monday at Annunciation Catholic School, officials said.

The gunman, identified publicly only as a man in his early 20s, was armed with a rifle, shotgun, and pistol, O’Hara explained. He used the rifle to fire shots from the outside, through the windows of Annunciation Church, while students and parishioners were attending a morning Mass.

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 deliberate act of violence against innocent children and other people worshipping. The sheer cruelty and cowardice of firing into a church full of children is absolutely incomprehensible,” said the police chief, who noted that wooden planks had been placed to barricade some of the church doors 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.

A law enforcement official told The Associated Press that authorities have identified the shooter as Robin Westman, but that official was not authorized to discuss the ongoing investigation and spoke on condition of anonymity.

Authorities have not yet determined whether the shooter had any connection to Annunciation but said he did not have a known extensive criminal history. A vehicle believed to belong to the shooter was going to be searched, O’Hara said, and the investigation remains ongoing.

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.