MINNEAPOLIS: The shooter who killed two Catholic school students and wounded more than a dozen children sitting in the pews of a Minneapolis church once attended the same school and had been a member of the church, the city’s police chief said.

Authorities were poring over videos, writings and the movements of the shooter but remained uncertain what motivated 23-year-old Robin Westman to open fire through stained-glass windows as children celebrated Mass on the first week of classes at the Annunciation Catholic School.

Minneapolis police chief Brian O’Hara said during a news conference Thursday afternoon that the shooter fired 116 rifle rounds into the church.

“Everything we’ve seen so far is a classic pathway to an active shooter,” O’Hara said earlier Thursday on on NBC’s “TODAY” show, adding that police have seen nothing “specific to trigger the amount of hate that occurred yesterday.”

Investigators recovered hundreds of pieces of evidence from the church and three residences, and are seeking warrants to search devices, the chief said. They found more writings from the suspect, but no additional firearms.