Members of a Lutheran church charities comfort dog ministry sit and stand in front of the Annunciation Catholic Church on Thursday in Minneapolis. (AP Photo/Abbie Parr)

MINNEAPOLIS (AP) — 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 and shooters,” Thompson said.

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.

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

Two children, ages 8 and 10, died in the shooting. City officials on Thursday increased to 15 the number of wounded children — ages 6 to 15 — in addition to three parishioners in their 80s who were also injured. Most were expected to survive, O’Hara said.

One child was in critical condition Thursday while 11 other victims remained in hospitals.

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.

On a YouTube channel, videos that police say may have been posted by the shooter show weapons and ammunition, and list the names of mass shooters. What appears to be a suicide note to family contains a confession of long-held plans to carry out a shooting and talk of being deeply depressed.

Rev. Dennis Zehren, who was inside the church with the nearly 200 children, said the responsorial psalm — which spoke of light in the darkness — had almost ended when he heard someone yell, “Down down, everybody down,” and gunshots rang out.

Fifth-grader Weston Halsne said he ducked for the pews, covering his head, shielded by a friend who was on top of him. His friend was hit, he said.

“I was super scared for him, but I think now he’s OK,” the 10-year-old said.

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.

Lily Kletter, who graduated from Annunciation, recalled that Westman joined her class at some point in middle school and once hid in the bathroom to avoid going to Mass.

“I remember they had a crazy distaste for school, especially Annunciation, which I always thought was pretty interesting because their mom was on the parish board,” she said.

Federal officials referred to Westman as transgender, and Minneapolis Mayor Jacob Frey decried hatred being directed at “our transgender community.” Westman’s gender identity wasn’t clear. In 2020, a judge approved a petition, signed by Westman’s mother, asking for a name change from Robert to Robin, saying the petitioner “identifies as a female and wants her name to reflect that identification.”

Annunciation’s principal Matt DeBoer said teachers and children alike responded heroically.

“Children were ducked down. Adults were protecting children. Older children were protecting younger children,” he said.

The city’s mayor called for a statewide and federal ban on assault weapons and high-capacity magazines at a City Hall news conference surrounded by officials and gun control advocates.

“There is no reason that someone should be able to reel off 30 shots before they even have to reload,” Frey said. “We’re not talking about your father’s hunting rifle here. We’re talking about guns that are built to pierce armor and kill people.”