All 14 children injured in Wednesday’s mass shooting in Minneapolis are expected to survive, the city’s police chief said at a press conference late Wednesday, with some victims having already been released from hospital.

An 8-year-old and 10-year-old sitting in pews were killed when a shooter opened fire through the windows of a church at the Annunciation Catholic School in Minneapolis at just before 8:30 a.m. on Wednesday morning, police said.

Seventeen people were injured, police said. Fourteen of the injured victims were children ages 6 to 15, while the three adults who were shot were parishioners in their 80s, O’Hara said.

The FBI identified the shooter as 23-year-old Robin Westman, who was born Robert Westman. The suspect died at the scene from a self-inflicted gunshot wound, police said.

Officers recovered three guns — one rifle, one shotgun and one handgun — at the scene, all of which are believed to have been fired in the attack. All were purchased legally by the suspect, officials said.

O’Hara told reporters on Wednesday night that authorities have four search warrants out for the church and three residences linked to the suspected shooter across the Minneapolis metro area.

Electronics related to the suspect were recovered by officers, but no other firearms, O’Hara said. Police are now working through dozens of pages from documents with assistance from the FBI in hopes of identifying a motive.

“It was premeditated, we believe,” O’Hara said, but added that investigators have not yet established a motive. The suspect had no criminal history, police said.

O’Hara said that additional police patrols will be provided as children return to school across the metro area throughout this week.

ABC News’ Mariama Jalloh, Pierre Thomas, Jack Date, Luke Barr, Aaron Katersky, Sasha Pezenik and Michael Pappano contributed to this report.