A shooter opened fire Wednesday morning during Mass at a Minneapolis Catholic school, killing two children and injuring 17 other people before killing himself, officials said.

Police said 14 of the injured were children, ages 6 to 15, and they are all expected to survive. The three adults who were injured are parishioners in their 80s, officials said.

The shooting happened at Annunciation Catholic School, just days after the first day of school on Monday.

Minneapolis Police Chief Brian O’Hara said all of the victims are expected to survive, though they have a range of injuries.

O’Hara identified the shooter as 23-year-old Robin Westman, adding that Westman had no prior criminal history and law enforcement believes he acted alone.

“There’s no words that’s going to ease the pain of the families today,” Minnesota Governor Tim Walz said at a news conference Wednesday afternoon.

The gunfire was the latest in a series of fatal shootings in Minnesota's most populous city in less than 24 hours.

One person was killed and six others were hurt in a shooting Tuesday afternoon. Hours later, two people died in two other shootings in the city.

AP video by Mark Vancleave