Image copyright Facebook Image caption Heather O'Brien with her daughter Darcy Dobson

A national virtual vigil will be held this week to honour the victims of Canada's deadliest shooting, which unfolded in Nova Scotia as the province was locked-down due to coronavirus.

Virus restrictions continue and authorities said they would not be lifted to allow public gatherings to mourn victims.

At least 18 people were shot dead by a gunman during a 12-hour weekend rampage.

The gunman was killed by police.

Who were the victims?

In the weeks leading up to her death, Heather O'Brien was busy caring for the elderly during the provincial-wide lockdown.

"First day off after 6 back tomorrow. First day I allowed myself to relax an inch," she wrote on her Facebook page on 9 April.

"My small space in life is marching on. I know atm [at the moment] all I love and cherish are ok. I am truly blessed."

Ten days later, Ms O'Brien would be killed near her hometown of Debert, Nova Scotia when a gunman disguised as a policeman killed at least 18 people, burning several buildings before dying in a shoot-out with police.

Media playback is unsupported on your device Media caption PM Trudeau: Canadians "heartbroken" after country's deadliest shooting

Ms O'Brien's daughter Darcy Dobson said on Facebook that "a monster" murdered her mother.

"The pain comes and goes in waves. I feel like I'm outside of my own body. This can't be real. At 9:59 am she sent her last text message to our family group chat. By 10:15 she was gone," she wrote Sunday evening, about ten hours after her mother was killed.

Ms Dobson said she wants "everyone to remember how kind she was" and how much she loved being a nurse and a grandmother, not "the horrible way that she died".

Ms O'Brien had continued to work on the front lines during the Covid-19 pandemic, as a home-care nurse with the non-profit Victorian Order of Nurses (VON), with whom she had been employed for 17 years. Another VON employee, Kristen Beaton, was also killed during the shooting.

Ms Beaton, worked for VON as a continuing care assistant and had been on the job when she was killed, according to her neighbour Penny Marchbank.

Image copyright Facebook Image caption Kristen Beaton was a young wife, mother and health care worker

She was married and had a young child.

"Kristen Beaton however will live on with all of the wonderful things she has done in her short lifetime and the thousands of lives she has effected in so many loving and wonderful ways," her neighbour said on Facebook.

VON president and CEO Jo-Anne Poirier told the BBC: "All of our frontline 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".

Constable Heidi Stevenson, who had served in the Royal Canadian Mounted Police force for 23 years, was on duty when she was killed.

Image copyright RCMP in Nova Scotia Image caption RCMP Constable Heidi Stevenson was killed responding to the attack

"Constable Stevenson died protecting others, she was answering the call of duty, something she had been doing with the RCMP for 23 years," Prime Minister Justin Trudeau said Monday during his daily press briefing.

"With unwavering courage & compassion, the RCMP patrol these roads to keep us safe as they have for hundreds of years."

Jenny Kierstead confirmed on Facebook that her sister, Lisa McCully, a mother of two, was also one of the victims.

Image copyright Facebook Image caption Lisa McCully, a mother of two, was a primary school teacher

McCully had been a school teacher at Debert Elementary School, according to the school's website.

"Our hearts are broken today as we attempt to accept the loss of my sister, Lisa McCully, who was one of the victims of the mass shooting in Portapique last night," she wrote on Facebook.

"Our condolences go out to the other family members who are affected by this tragedy. Thank you for your support, it's a hard day."

Not all the victims - all adult men and women, according to police - have been named.

The CBC reported that correctional officer Sean McLeod and his partner Alanna Jenkins were among the victims.

An online fundraiser has been set up to help pay for the funeral costs of a family of three, Jolene Oliver her husband Aaron (Friar) Tuck and their daughter Emily Tuck.

Ms Oliver's sister Tammy Oliver-McCurdie began the fundraiser, and says her niece was 17 years old, played the fiddle and enjoyed fixing cars with her dad.

Married couple Jamie Blair and Greg Blair were killed Sunday, according to a relative.

"My family has been through so much, no one should have ever had to deal with this. I love you both so much, & sending all my love to my family & every other families who lost someone today," said Jessica MacBurnie on Facebook.

The Globe and Mail reported that Corrie Ellison, a social worker worker in his 40s, was also among the victims.

Charlene Bagley said her father, Tom Bagley, died while checking in on an explosion that was allegedly caused by the gunmen.

"He died trying to help, which if you knew him, you knew that was just who he was all the time. I know he meant something to so many people," she said on Facebook.

What do authorities know about the shooting?

The deadliest shooting in modern Canadian history unfolded over 12 hours at the weekend, beginning on Saturday near the rural town of Portapique.

Little is known about what motivated the suspected shooter, 51-year-old Gabriel Wortman, or how he chose his victims.

At about 23:32 on Saturday (02:32 GMT on Sunday), officers responded to a "firearms complaint" at a home and advised residents to lock themselves indoors.

The officers found "several casualties" inside and outside the home, but did not find the suspect.

A neighbour told CBC News that he saw three properties were also on fire in the area at the time.

The gunman was identified on Sunday after carrying out shootings over a series crime scenes that police said were "scattered across the province".

Authorities are in the early stages of the "extremely complex investigation", said Chief Superintendent of the Nova Scotia RCMP Chris Leather.

Including the suspect, there are some 19 victims across 16 crime scenes, including five structure fires, Mr Leather said on Monday.

"We believe there may be victims within the remains of those homes which burned to the ground," Mr Leather said.

Some victims were known to the suspect but others were selected at random, Mr Leather said, though he would not elaborate on the nature of these relationships.

At some points in the 12-hour rampage, the suspect travelled in a car made to look like an RCMP cruiser. The replica looked "identical in every way" to an authentic one, Mr Leather said.

He also wore an RCMP uniform, either an "actual uniform or very good facsimiles", he said.

"The fact that this individual had a uniform and a police car at his disposal certainly speaks to it not being a random act."

RCMP officials say more victims may be identified in the remains of some of the burnt-out buildings.

Due to provincial restrictions on public gatherings put in place to stop the spread of Covid-19, there can be no mass public vigil.

Instead, a national online vigil will be held on Friday evening, which Prime Minister Justin Trudeau says he will attend virtually.

"As we learn more about what happened yesterday, it important that we come together to support communities," he said Monday.

Mr Trudeau said that his Liberal party was "on the verge" of introducing bans to assault style weapons before parliament was dissolved amid the coronavirus outbreak.

"We have every intention of moving forward", once the outbreak is curbed, he said.

The White House sent condolences from US President Donald Trump.

"The United States and Canada share a special, enduring bond," a statement read.

"As friends and neighbours, we will always stand with one another through our most trying times and greatest challenges. The United States strongly condemns these murders, and our prayers are with the victims and their families."