India, Aug. 28 -- In the aftermath of the deadly mass shooting at a Catholic school in Minneapolis, police have revealed what may have prevented an "unthinkable" tragedy from being worse. Minneapolis Police Chief Brian O'Hara has said that locked doors during Mass may have helped the attack at Annunciation Catholic Church from becoming a bigger tragedy.

"A number of the doors had been locked once Mass began, which is part of their normal procedure," O'Hara told CNN's Kaitlan Collins. "We believe that this step also played a part in ensuring this tragedy did not become that much worse."

Shooter Robin Westman killed two children, aged 8 and 10, and injured several others after opening through the stained glass windows of Annunciation Cath...