Canada’s worst mass shooting, last weekend’s rampage in Nova Scotia, happened after an argument between the gunman and his girlfriend spiraled out of control, a police official has said. The official confirmed to the Associated Press late Thursday that the shooting spree, which left at least 22 people dead, erupted from a domestic dispute involving 51-year-old denturist Gabriel Wortman and his partner. The unnamed official said more details would be given at a Friday news conference. Wortman was shot and killed about 13 hours after the attacks began. He carried out much of the attack while in disguise as a police officer in a vehicle made up to appear like a patrol car. There are 16 crime scenes in five different communities throughout Nova Scotia.