TORONTO -- At least 18 people died in the weekend killing rampage in Nova Scotia and investigators fear that number will rise as they probe 16 crime scenes.

It could take months to unravel the lone suspect’s violent path across the province Saturday night and into Sunday. The suspect was killed Sunday after police intercepted him near a gas station.

The crime scenes include five structure fires where RCMP believe more fatalities may be found, Chief Supt. Chris Leather said at a media update Monday afternoon. It is already among Canada’s worst mass killings.

Police said they searched for the suspect for about 12 hours from late Saturday night into Sunday morning, as he travelled more than 150 kilometres along rural roads and highways, killing victims and torching properties and police vehicles.

Const. Heidi Stevenson, a 23-year veteran of Nova Scotia’s RCMP, was among the victims of the rampage.

In a bit of good news, the RCMP officer injured in the mass killing in Nova Scotia is recovering, investigators revealed.

Leather said Const. Chad Morrison, an 11-year RCMP veteran who was shot Sunday, is now recovering at home.

Some of the victims were known to their killer and others were not, Leather said. He would not comment on the nature of any relationship between the suspect and any victim or any motive.

Leather says the RCMP’s investigation into the attack could take months.

“The full scope of this tragedy … will be remembered throughout Canada’s history,” said Public Safety Minister Bill Blair at a news conference in Ottawa Monday.

He said the RCMP is embarking on a long and complicated road ahead in terms of “getting Canadians the answers that they seek” and they are doing so while mourning a “beloved colleague.”

“Our hearts are broken. My heart is broken. This is a senseless, unprecedented act of violence,” said RCMP Commissioner Brenda Lucki, who spoke alongside Blair.

She said her organization is getting expression of condolences from across Canada and around the world.

“Our focus is to put names to victims and to the heroes who served their communities.”

POLICE WATCHDOG PROBING THREE ISSUES

Meanwhile, the province’s police watchdog, the Serious Incident Response Team (SIRT), is investigating three separate issues relating to the investigation, Leather said. It was immediately called in to take a look at the shooting of the suspect, Gabriel Wortman, who was cornered by police at a gas station in Enfield, N.S. late Sunday morning.

The SIRT is now probing two other incidents “that came to light pursuant to our investigation,” said Leather. He said they relate to use of force and involve two members of the RCMP. He declined to say anything further.

Investigators are not looking for any additional suspects related to the shooting spree, said Leather, adding that RCMP will build a timeline of the killer’s travels and crimes in the coming days.

“His ability to move around was certainly aided by the fact he had what looked like a police vehicle and that he was wearing a police uniform.” It’s unclear, says Leather, whether that uniform was a fabrication or a real one.

CTV News public safety analyst Chris Lewis told CTV New’s Your Morning on Monday that the RCMP has deep resources and expertise, but this will be a challenging investigation because of the wide course of the suspect’s path and multiple crime scenes.

“This is huge. Normally a shooting like this happens in one location, either on a street in a city or in one building, etcetera. But this is something like we’ve never seen before,” Lewis, who retired as the commissioner of the OPP in 2014.

Police said that, at one point, the suspect was driving what appeared to be an RCMP vehicle and wearing an RCMP uniform -- though he was not an RCMP officer.

Lewis says the apparent premeditation of the attack is “absolutely evil like we have never seen in Canada.”

Leather was asked Monday afternoon about reports that the suspect was able to commandeer an actual police vehicle and firearms. “He was never driving an actual police car at any time that we are aware of,” he answered. But he would not comment on whether the shooter was in possession of police firearms because that is part of the SIRT investigation.

The suspect did steal vehicles from citizens when the vehicle made to look like an RCMP vehicle he initially used became undriveable, Leather said.

TWEETS INSTEAD OF EMERGENCY ALERT

RCMP officials said Monday that the ensuing investigation will look into how the threat was communicated to the public as it developed over the course of many hours.

The police force opted to use Twitter instead of the province’s emergency alert system to warn people about the active shooter. Premier Stephen McNeil said Monday that that system wasn't used because the province's Emergency Measures Organization did not receive a request from the RCMP to issue an alert.

But McNeil was quick not to place any blame on the police force, saying it was not the time to “second guess” the organization. “This was an active environment -- deaths, gunfire -- let's give them an opportunity as an organization to explain that,” he said.

Chief Supt. Leather told reporters that the Twitter account was used since it has thousands of followers and the police force determined it was “a superior way to communicate this ongoing threat.”

RCMP Commissioner Brenda Lucki said that the organization would probe the Twitter question in its investigation. “In any incident such as this, we always have to look back at what we did,” she said.

Leather said he didn’t have information about how many people might remain in hospital with injuries.

Though the identities of some victims are now coming to light, police will not release names of victims without formal identification from the medical examiner’s office, said Leather.

Prime Minister Justin Trudeau praised the work of first responders, especially Stevenson.

“Constable Stevenson died protecting others. She was answering the call of duty, something she had done every day when she went to work for 23 years,” Trudeau said Monday, during his near-daily address to Canadians.

“This tragedy is a painful reminder of the risks all of our first responders take to keep us safe, of the sacrifices they make every single day to protect our communities. Paramedics, doctors, nurses, firefighters and police officers. They’re always here for us. They've been stepping up through the pandemic and yesterday in Nova Scotia they showed that bravery.”

Trudeau said Canada joins together in mourning all the victims of what he called a “senseless act of one person.”

“For the grandparent who lost a child, the children who lost a parent, the neighbour who lost a friend, we are so sorry for your loss. Such a tragedy should have never occurred, violence of any kind has no place in Canada. We stand with you, we grieve with you, and you can count on our government’s full support during this incredibly painful time.”

SEVERAL PEOPLE FOUND DEAD AT PORTAPIQUE HOME

The incident began late Saturday evening when police responded to a residence in Portapique after receiving several 911 calls about an active shooter.

There, police found an unnamed number of casualties, both inside and outside the home.

Officers secured the area in Portapique, which is approximately 130 km north of Halifax and 40 km west of Truro, and started what would become a 12-hour manhunt.

The RCMP warned residents of the area, already in lockdown because of the pandemic, to lock their doors and stay inside. Later, investigators revealed that the suspect was driving what was made to look like an RCMP cruiser and was possibly wearing a fake uniform. The suspect, who owned two denture clinics in the Halifax area, has never been a member of the RCMP.

Investigators first released the suspect’s identity – Gabriel Wortman, 51 – before 9 a.m. Sunday.

SUSPECT SHOT AND KILLED IN ENFIELD

Officers eventually tracked Wortman to the Irving gas station and Big Stop restaurant in Enfield, N.S., about 90 kilometres away from Portapique, where he was shot and killed late Sunday morning.

A truck driver from Ontario told CTV News he had stopped at the Irving for a shower and breakfast when he heard an employee shouting.

“She goes, ‘Oh my God, lock the doors, he’s here! And I peek out of the window and I saw some RCMP vehicles and there was four or five uniforms with guns,” said Tom Nurani.

Witnesses told CTV News they saw RCMP vehicles on scene, heard multiple gunshots, and saw a body on the ground.

“All I could hear was gunshots and my wife, I thought I was going to call 911, because she was going into panic, it scared her so bad,” said Glen Hines, who was driving by the Irving when he saw the Emergency Response Team arrive.

“There was multiple, like probably between five or 10 (gunshots). It was steady,” recalled Deon Wells, who lives nearby.

MORE VICTIMS IDENTIFIED

Two employees of Victorian Order of Nurses for Canada are among the dead, according to the home care agency. A statement from president and CEO Jo-Anne Poirier issued Monday morning, says the victims are Heather O’Brien and Kristen Beaton.

O’Brien was a licensed practical nurse and a wife, mother and grandmother. She had worked as a VON nurse for nearly 17 years. Beaton was a continuing care assistant, and a wife and mother. She worked for VON for nearly six years.

“All of our front-line care providers are heroes. Yesterday, two of those heroes, Heather O’Brien and Kristen Beaton, were taken from their families, and from VON. We mourn their loss, and we mourn for their families.”

The Nova Scotia Teachers Union issued a statement Sunday that said a teacher at Debert Elementary, Lisa McCully, was among the dead.

She was known by colleagues and students “not only as a passionate teacher but as a shining love in their lives.”

The statement, signed by president Paul Wozney, also said that Dean Stevenson, husband to the RCMP officer who was killed, teaches at Cole Harbour District High School.

“We know that there are many others who died last night whose families are struggling to process what has happened,” Wozney wrote. “Their lives are no less precious. They are our neighbours and friends. Their children are our students. We hurt with you all too.”

‘EMOTIONAL TOLL’

Lewis says officers who are part of the response and investigation, and those who were friends and colleagues of Stevenson, will experience “a lot of emotional trauma.”

He says many of them will need support from their peers and help from clinical experts.

“The emotional toll is huge.”

And that toll comes during a pandemic lockdown, meaning there can be no funerals or public gatherings to share grief.

RCMP Sgt. Joe Taplin, who worked with Stevenson, says the province’s small and close-knit division is experiencing shock. Virtually everyone will have worked with or crossed paths with the fallen officer, he told CTV’s Your Morning on Monday.

He can’t recall her without a smile on her face and she was devoted to her family. Taplin says Stevenson was outgoing and caring and served on the RCMP’s famed Musical Ride, an equestrian showcase that performs across Canada and around the world.

“Heidi was an amazing, wonderful, beautiful person,” he said. “She gave so much to her community and she was a loving wife and mother.”

Taplin says the RCMP has a job to do while coping with being “totally devastated” by the loss of life in the province.

“We are hurting from coast to coast to coast … It’s a very sad day.”

Todd Battis, Atlantic bureau chief for CTV News, says though the trail of violence spans perhaps 150 km, the population of the region is small and closely connected. In fact, Battis graduated from the same New Brunswick high school class as the suspect.

“As the stories of these victims come out, because there are simply so many in the region, I think you’ll find that almost everybody will have some sort of connection or will know somebody who has a connection to these victims,” he said on Your Morning.

“And the focus should be on the victims. And it will be.”

He said the suspect’s high school yearbook profile said that he might be an RCMP officer one day.

THE SUSPECT

A Gabriel Wortman is listed as a denturist in Dartmouth, according to the Denturist Society of Nova Scotia website. A suspect photo issued by the RCMP matches video footage of a man being interviewed about dentures by CTV Atlantic in 2014.

Some Portapique residents who spoke with The Canadian Press said they knew him in passing as a part-time resident who divided time between the Halifax area and his properties in the community. Portapique’s population numbers about 100 in the summer months, but swells to about 250 during summer cottage season.

David George Crockett, who lives a three-minute drive from Portapique Beach Road, the area where the first 911 calls originated, said Wortman once fixed his teeth at his home in Portapique.

"I'm very surprised," Crockett said in a brief interview outside his rural home. "I never thought he would do something like that."

“From what I knew of him, he was quiet, gentle and very easy to talk to .... He was very nice. He kidded around a little bit. He seemed normal, not like someone who would do something like this."

A little farther down the rural road, another neighbour said he and Wortman were friends until the two had a falling out over a piece of nearby property.

The neighbour, who declined to give his name, said Wortman had burned an old shed that contained some property that belonged to the neighbour. The man said he was too overcome with emotion to say more about his relationship with Wortman or what might have motivated his rampage.

Christine Mills, another resident, said it had been a frightening night for the community, which was suddenly filled with armed officers patrolling the streets. In the morning, helicopters flew overhead searching for the suspect.

She said she was fearful the shooter might have gone through the woods and attempted to enter her home.

"It's nerve-wracking because you don't know if somebody has lost their mind and is going to beat in your front door," she said.

Tom Taggart, a councillor who represents the Portapique area in the Municipality of Colchester, said the quiet community is in shock.

"This is just an absolutely wonderful, peaceful quiet community, and the idea that this could happen in our community is unbelievable," Taggart said by phone from his home in Bass River, about three kilometres away from Portapique.

Taggart said he didn't know Wortman well, but spoke to him a few times when he telephoned about municipal issues, and described knowing Wortman's "lovely big home" on Portapique Beach Road.

With files from CTV Atlantic's Andrea Jerrett and The Canadian Press