The toll from the worst mass shooting in Canada's modern history, a 14-hour rampage over the weekend, has risen to 22 from 19, police say.

The victims include a 17-year-old, a pregnant healthcare worker and a veteran Royal Canadian Mounted Police (RCMP) officer.

Authorities are yet to determine a motive for the crime. Police say the gunman knew some of the victims.

The gunman, a 51-year-old man, was killed in a confrontation with police.

During the attack he wore an authentic RCMP police uniform and drove a "look-alike" police vehicle, authorities said.

Nova Scotia RCMP updated the death toll from the attack in a statement on Tuesday along with a rough timeline of the events.

Police had previously warned the number of dead could rise as they searched the 16 separate crime scenes across north and central Nova Scotia.

Their work was also slowed by the fact there were a number of fires started - about five, according to police. They had to search through the debris of those badly burnt-out homes for remains.

The full investigation is likely to take months.

The attack began around 22:30 on Saturday (01:30 GMT) in the rural beachside community of Portapique.

Police received multiple calls to the emergency services reporting gunshots, and responders found "several casualties inside and outside of a home" but no suspect.

They also discovered "multiple sites in the immediate area, including structures and vehicles that were on fire".

The suspect's vehicle was found at the crime scene where 23-year RCMP veteran Const Heidi Stevenson was killed in the line of duty.

Victims were also found in the communities of Wentworth, Debert, Shubenacadie/Milford and Enfield, where police shot the gunman dead.

Little is known about what motivated the suspect, Gabriel Wortman, or why he chose his victims.

Among the dead were a teacher, a home care nurse working on the frontlines of the coronavirus pandemic, and an RCMP officer. 

A national virtual vigil will be held this week to honour the victims of the shooting, as the province is locked-down due to the virus. 

Many other virtual vigils have since sprung up on social media as people mourn the tragedy. 

The first victim made public was Const Stevenson, a 23-year veteran of the force and a mother of two.

Another was Heather O'Brien, who was caring for the elderly with the non-profit Victorian Order of Nurses (VON), during the provincial-wide lockdown before she was killed near her hometown of Debert, Nova Scotia.  

Another VON employee, Kristen Beaton, was also killed during the shooting.

Lisa McCully, a mother of two, was among the victims. McCully had been a school teacher at Debert Elementary School, according to the school's website.

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

Sean McLeod and his partner Alanna Jenkins were among those killed. Their neighbour, Tom Bagley, also died, apparently while checking in on the couple on Sunday morning.

"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," his daughter Charlene Bagley said on Facebook.

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.

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.

One police officer - Const Chad Morrison - was injured during the rampage but is recovering. 

Police said on Tuesday they have "information that other members of the public have been injured as well" but did not offer more details. 

BBC