MINNEAPOLIS — The shooter who killed two Catholic school students and wounded more than a dozen youngsters sitting in the pews of a Minneapolis church once attended the same school and was “obsessed” with the idea of killing children, authorities said Thursday.

The shooter, identified as 23-year-old Robin Westman, fired 116 rifle rounds through stained-glass windows while the children celebrated Mass during the first week of classes at the Annunciation Catholic School, said Minneapolis police Chief Brian O’Hara.

“It is very clear that this shooter had the intention to terrorize those innocent children,” O’Hara said.

Acting U.S. Attorney Joe Thompson said videos and writings the shooter left behind show that the shooter “expressed hate towards almost every group imaginable.”

The only group Westman did not hate was “mass murderers,” Thompson said. “In short, the shooter appeared to hate all of us.”

Investigators recovered hundreds of pieces of evidence from the church and three residences, the police chief said. They found more writings from the suspect, but no additional firearms or a clear motive for the attack on the church the shooter once attended. Westman had a “deranged fascination” with mass killings, O’Hara said.

“No evidence will ever be able to make sense of such an unthinkable tragedy,” he said.

Surveillance video captured the attack and showed the shooter never entered the church and could not see the children while firing through windows lined up with the pews, the police chief said.

Family members described one of the victims, 8-year-old Fletcher Merkel, as a boy who loved his family, fishing, cooking and any sport he was allowed to play.

“We will never be allowed to hold him, talk to him, play with him and watch him grow into the wonderful young man he was on the path to becoming,” his father, Jesse, said while tearfully reading a statement outside the church on Thursday.

The parents of the other victim, 10-year-old Harper Moyski, said in a statement that she was a bright and joyful child.

“Our hearts are broken not only as parents, but also for Harper’s sister, who adored her big sister and is grieving an unimaginable loss,” said Michael Moyski and Jackie Flavin. “As a family, we are shattered, and words cannot capture the depth of our pain.”

They said they hope her memory helps drive leaders “to take meaningful steps to address gun violence and the mental health crisis in this country.”

The Hennepin County Medical Examiner’s office said they both died of gunshot wounds.

City officials on Thursday increased to 15 the number of injured children, who are ages 6 to 15. Three parishioners in their 80s also were injured. Only one person — a child — was in critical condition.

Westman, whose mother worked for the parish before retiring in 2021, left behind several videos and page upon page of writings describing a litany of grievances. One read: “I know this is wrong, but I can’t seem to stop myself.”

O’Hara said Westman was armed with a rifle, shotgun and pistol, and died by suicide.

Minnesota Gov. Tim Walz on Thursday sent state law enforcement officers to schools and churches in Minneapolis, saying no child should go to school worried about losing a classmate or gunshots erupting during prayer.

There were no past arrests or anything in the shooter’s background that would have prevented Westman from being able to legally purchase a firearm, investigators said Thursday.