TORONTO (AP) — Canada’s worse mass shooting started as a domestic dispute between the gunman and his girlfriend, who survived the attack, a police official said late Thursday.

The official confirmed to The Associated Press that the weekend rampage in Nova Scotia erupted after an argument between the pair. The official, who spoke on condition of anonymity, said more details would be provided at a news conference Friday.

Police have said 51-year-old Gabriel Wortman acted alone in waging a shooting spree that killed at least 22 people across northern and central Nova Scotia. There are 16 crime scenes in five different rural communities throughout northern and central Nova Scotia.

The suspect was shot to death Sunday morning, about 13 hours after the attacks began.

Several bodies were found inside and outside one house in the rural town of Portapique, police have said. Bodies were also found in four other communities, and authorities believe the shooter targeted his first victims but then began attacking randomly as he drove around.