FREDERICTON -- Two days after four people were gunned down in a quiet Fredericton neighbourhood, the city's Pride parade went ahead Sunday, with the mayor saying: "There's a way to celebrate even in the midst of this grief."

Prime Minister Justin Trudeau went to Fredericton Sunday to attend a Pride-related event and meet with police officers and their families as he offers his condolences to the community.

Mayor Mike O'Brien said the parade was a way for Fredericton's residents to begin healing in the wake of the shooting that killed Bobbie Lee Wright, Donnie Robichaud, Const. Robb Costello and Const. Sara Burns at a north-side apartment complex.

"It's a way for our community to start rebuilding our faith in community and having a celebration," O'Brien said Saturday.

It began with a moment of silence, and parade organizers said in a Facebook post that they were marching "in appreciation of our Chief of Police Leanne Fitch, the first responders, and all the officers who risk their lives on a daily basis to keep us safe."

Describing the victims as "husbands, wives, sons, daughters, brothers, sisters, uncles, aunts, friends," the mayor said he knows the community will "heal together."

The Fredericton Police Force's public information officer, Alycia Bartlett, said in a release Sunday afternoon that a regimental funeral will be held for Burns and Costello. Details have not yet been released.

She also said that a book of condolences will be available to the public in the council chambers of Fredericton City Hall on Monday.

There has been an outpouring of grief in the small city, with residents stopping by the Fredericton Police Force's headquarters to drop off flowers, notes and teddy bears for the fallen officers.

"I want to extend my sincere thanks to all of you on behalf of the Fredericton Police Force," Fitch said in a written statement Sunday.

"Your support, as demonstrated by the flowers and cards that are left in front of the police station is appreciated by us all. Everyone in our community is hurting with the deaths of four of our citizens but the support of the community, to our fallen officers, the two others killed and all of their families and friends is appreciated."

After meeting privately with police officers, Trudeau was to lay flowers outside their headquarters, and then in the early evening attend what was described as a "Fredericton Pride social event" at a local pub.

In a written statement issued by Jackie McLean, Costello's common-law partner, she described the 20-year police veteran as the most positive person she's ever met and said he always came home from work with "a smile on his face."

"My heart goes out to the other families who are also suffering from this tragedy," wrote McLean, who also goes by Jackie Steeves. "So many other officers and friends share in this loss and my heart breaks for each of you as it breaks for me."

A statement on behalf of Burns' family said the officer loved her job and "went to work each shift committed to serving this great community."

Both families have asked for privacy as they continue to grieve.

Meanwhile, friends of Robichaud and Wright have taken to social media to express their sorrow, and a GoFundMe campaign to benefit their families has already amassed thousands of dollars.

Robichaud, 42, had just begun dating Wright, 32, in August.

Ten children lost a parent Friday morning -- Burns was married with three kids, while Costello was a father of four and Robichaud had two teenage sons and an older daughter.

A team of volunteers with the Canadian Red Cross has helped arrange emergency lodging for 46 people displaced by the investigation. At least eight other people were staying with family or friends.

Matthew Vincent Raymond, 48, has been changed with four counts of first degree murder and is set to appear in court on Aug. 27.

Raymond was shot by police on Friday and was still being treated in hospital for his injuries as of Saturday. Police did not say how serious his injuries were.

Two investigators with Nova Scotia's Serious Incident Response Team, a police watchdog agency, were dispatched to Fredericton on Friday to investigate police involvement in Raymond's injuries.

Police did not say if the suspect and victims were known to each other and a motive is not yet known.

-- By Alex Cooke in Halifax