By the time Gabriel Wortman, 51, was killed in a shootout at a gas station in Nova Scotia, at least 19 people had died by his hand, including healthcare workers, a member of the Royal Canadian Mounted Police and an elementary school teacher.

On Monday, the victims' loved ones began sharing their grief with the world.

Nurse Heather O'Brien was one of those killed during Wortman's attack. The day after the shooting, Ms O'Brien's daughter wrote a post about her mother on Facebook.

"A Monster murdered my Mother today. Murdered her, without a second thought. The pain comes and goes in waves. I feel like I'm outside of my own body. This can't be real," Ms O'Brien's daughter wrote.

She said she didn't want her mother's death to be her defining moment.

"I want everyone to remember how kind she was. How much she loved being a nurse. The way her eyes sparkled when she talked to her grandchildren and the way she just LOVED Christmas. Let those things define her. Not the horrible way she died," she wrote.

Ms O'Brien's colleague at the Victorian Order of Nurses, Kristen Beaton, also died in the attack.

Ms Beaton was also a mother and was working the day of the shooting.

Constable Heidi Stevenson was also among those killed. She was a 23-year veteran with the Royal Canadian Mounted Police and a mother of two.

RCMP assistant commissioner Lee Bergerman issued a statement lamenting Ms Stevenson's death.

"What has unfolded overnight and into this morning is incomprehensible and many families are experiencing the loss of a loved one. That includes our own RCMP family," Ms Bergerman said. "Heidi answered the call of duty and lost her life while protecting those she served."

Ms Bergerman said she'd met Ms Stevenson's family to offer her sympathies.

"Earlier this afternoon, I met with Heidi's family and there are no words to describe their pain. Two children have lost their mother and a husband his wife," she wrote.

Lisa McCully, who The Globe and Mail reported was a third and fourth grade teacher, also died during the massacre.

The Nova Scotia Teachers' Union president Paul Wozney issued a statement lamenting her death.

"[Our] hearts are broken along with those of her colleagues and students at Debert Elementary, as well as her family and friends who knew her not only as a passionate teacher but as a shining love in their lives," Mr Wozney wrote.

Ms McCully's sister, Jenny Kierstead, posted a Facebook message talking about her friend's death.

"This is so hard to write but many of you will want to know. 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. "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."

In addition to the aforementioned victims, The Globe and Mail also listed the following individuals among the dead:

Sean McLeod and Alanna Jenkins were a married couple employed as correctional officers. Mr McLeod worked at the Springhill Institution and Ms Jenkins worked at the Nova Institution for Women.

Jolene Oliver, Aaron (Friar) Tuck and Emily Tuck were a married couple and their 17-year-old daughter.

Jamie and Greg Blair were a married couple with two young children. Mr Blair had two sons from a previous relationship.

Gina Goulet was a dental technician and cancer survivor.

Corrie Ellison was a social service worker who was visiting his father in Portapique the night of the murders.

Though facts are still coming to light, initial police reports suggest the shooter was dressed as a member of the RCMP and was driving around in a car made to look like an official police car.

Police said that as the shooter progressed, he set people's homes on fire and shot them as they ran outside.