Authorities on the east coast of Canada were searching for a motive today after a gunman who appeared to be dressed as a police officer and was driving a vehicle that looked exactly like a genuine police car killed at least 19 people in one of the country’s worst mass shootings.

Prime Minister Justin Trudeau of Canada implored his nation, which like many others is reeling from the coronavirus pandemic, to stand together despite this new trauma, “no matter how evil, how thoughtless or how destructive.”

The gunman, Gabriel Wortman, 51, who ran a denture clinic in Nova Scotia, began the massacre in the town of Portapique on Saturday night and did not stop until he died 12 hours later at a gas station in Enfield, 22 miles away, authorities said. Police have not said how he died, which is the subject of a separate investigation by an oversight body.

Chief Superintendent Chris Leather of the Royal Canadian Mounted Police in Nova Scotia said today that the force believes that it will find additional victims in the remains of five burned out buildings, most of them homes. All the known victims are adults, he said.

Aside from a Mountie, who was at home recovering from a gunshot wound today, the police force said it remains unclear how many other people were wounded in the rampage.

The killings shocked Canada, which is already grappling with how to stop the coronavirus, and while there was no immediate motive given, police said one line of investigation would be whether it had played a role.

Heather O’Brien, a nurse, was one of the victims of the shooting. Her daughter, Darcy Dobson, wrote in a Facebook post Sunday that “a monster murdered my mother today.”

“She drove down the same street in the same town she drives through every single day,” Dobson wrote, saying her mother had texted their family group at 9:59 a.m. Sunday. “By 10:15 she was gone,” she said.

The Victorian Order of Nurses for Canada, O’Brien’s employer, said Kristen Beaton, a continuing care assistant, was killed. A police officer and an elementary schoolteacher were also among the victims of the attack, which was described by Stephen McNeil, the premier of Nova Scotia, as “one of the most senseless acts of violence in our province’s history.”

Wortman was a denturist, a licensed dental health professional who works with dentists and provides denture care directly to customers. Denturists examine patients who are missing teeth and can design, construct and repair removable dentures.

In 2014, Wortman was in the news in Canada for a different reason: He was creating a new set of dentures, free of charge, for a cancer survivor who had lost all her teeth.

“My heart went out to her,” he told a Canadian TV network at the time.

She had cried tears of happiness, speaking of the “angels” who came to her aid.

Much remains unknown about the killing spree. Leather said that there are 16 crime scenes.

The suspect, he said, had been able to elude the police for almost 12 hours largely because he was traveling in a homemade version of a Royal Canadian Mounted Police cruiser, which Leather said “looked identical in every way” to a real one. He was also wearing RCMP clothing that, Leather said, “were either actual uniforms or very good facsimiles.”

After the bogus police cruiser was eventually engulfed in fire, Wortman switched to a large SUV he apparently took by force from a member of the public.

The killing spree began in the cottage community of Portapique where Wortman owned several properties. At first, Leather said, the shootings appeared to be targeted and involved victims known to Wortman. They then became random and his victims were apparently strangers.

But Leather declined to say if the rampage started at one of Wortman’s properties or if the victims include his family members.

Commissioner Brenda Lucki, head of the Royal Canadian Mounted Police, said in Ottawa that Wortman “was not well known to police.”

She added that no note or other communication by Wortman had been found. She declined to identify the types of weapons he used. Nor would she say if Wortman held a firearms license.

Jenny Kierstead, whose sister, Lisa McCully, was the schoolteacher who died in the attack, said “our hearts are broken today as we attempt to accept the loss.”

Another victim was Heidi Stevenson, an officer with the Royal Canadian Mounted Police with 23 years of experience on the force and a mother of two. She died after she responded to the shooting.

“Heidi answered the call of duty and lost her life while protecting those she served,” the police said in a statement.

Another officer was injured.

Trudeau called for unity at a news conference today.

“No one man’s action can build a wall between us and a better day, no matter how evil, how thoughtless or how destructive,” Trudeau said. “As families grieve the loss of a loved one all Canadians are standing with them.”

Because of the coronavirus pandemic, Trudeau said that a national vigil for the victims will be held online Friday.

Those who knew Wortman described him as having been “a little different,” but they were nonetheless shocked to hear he had been identified by authorities as the perpetrator of such a bloody attack.

“Gabriel always had a sadness about him, but I was so shocked to hear that he’d hurt other people,” Candy Palmater, a university friend, told local news outlets Sunday. “I don’t know what his later adult life was like, but I can tell you that at university, people weren’t nice to him.”

She said she couldn’t reconcile what he had done with the man she knew.

Scott Balser, a former high school friend, said Wortman “was a very nice guy who liked to help others,” according to The Chronicle Herald, a newspaper in Nova Scotia.

Sophie LeBlanc, a woman who wrote on Twitter that her mother went to high school with Wortman, posted a photo of his yearbook entry.

“Gabe’s future may include being an RCMP officer,” it said.