At least 16 people, including a police officer, were killed in a shooting incident in Canada’s Nova Scotia province on Sunday, believed to be the worst that the country has seen, AFP reported. The attacker, who was dressed as a policeman, was shot dead by the police after a 12-hour search operation.

The police said that the suspect had been on the run since Saturday night, when officers were alerted about firing in Portapique town, around 100 km from Halifax.

Heidi Stevenson, a Royal Canadian Mounted Police official, was killed while responding to the attack. “What has unfolded overnight and into this morning is incomprehensible and many families are experiencing the loss of a loved one,” Nova Scotia Royal Canadian Mounted Police Commanding Officer, Assistant Commissioner Lee Bergerman, posted on the force’s Facebook page. “It is with tremendous sadness that I share with you that we lost Constable Heidi Stevenson, a 23-year veteran of the Force.”

Royal Canadian Mounted Police Chief Superintendent Chris Leather said that they have no indication of a motive yet. “We are in the early stages of an incredibly detailed and complex investigation that has forever changed countless lives,” he said. “What I would say is that it appears to be at least in part, very random in nature.”

Prime Minister Justin Trudeau expressed his grief over the incident. “To those who lost loved ones following the senseless violence in Nova Scotia, and to the @RCMPNS family, know Canadians across the country are mourning with you,” he said in a statement.