FREDERICTON -- Hundreds of mourners lined around a downtown Fredericton building Thursday for an emotional public visitation for two city police constables killed in the line of duty.

Constables Robb Costello and Sara Burns were gunned down at an apartment complex on Fredericton's north side Friday, in a shooting that also claimed the lives of civilians Bobbie Lee Wright and Donnie Robichaud.

Inside a dimly-lit ballroom of the Fredericton Convention Centre, the families of Costello and Burns stood near large framed photographs of the fallen officers as a steady stream of visitors paid their respects to the grieving families.

Two large projectors on either side of the room played slide shows with pictures of the officers at different stages of their lives, from what appeared to be a high school graduation and prom night to cradling a newborn baby and apple picking.

Many people left the visitation in tears, struggling to cope with the violent shooting that has gripped this city for the last week.

The Burns family issued a public statement Wednesday saying "we have heard one common theme since the passing of Sara and Robb."

"They were two of the most positive people anyone had ever met," said Burns' husband, Steven Burns.

An obituary said the 43-year-old Burns fulfilled her lifelong dream of becoming a police officer three years ago, after more than 14 years as a stay-at-home mom of her three boys.

"Not a day would go by when she didn't say aloud, for everyone to hear, 'I love my job,"' the obituary published on the McAdam's Funeral Home and Crematorium website said.

Steven Burns said his wife could "brighten a room with her smile in an instant and make anyone feel at ease seconds later with just a few words."

"Sara was put on this earth to help people and everything she has ever done in life was to help people," Burns said. "We are so proud of the person and human being that she was, and we will miss her dearly."

An obituary for Costello said he loved being a police officer and though he spent time in specialized units he eagerly went back to patrol, "his true love," the obituary published on the Bishop's Funeral Home website said.

"He was away at the police academy while his first daughter (Kassie) was an infant," the obituary said.

"He joined the Fredericton Police Force immediately after finishing the academy. His daughter Kaitlyn was born in Fredericton and Robb had a strong connection to the city he served."

Costello was "so proud of both his girls and the women they were becoming," the obituary said.

"To his step-children he was known as 'Faux Pa' and he loved them like they were his own."

On Saturday, thousands of police officers and first responders from across the country are expected to attend a regimental funeral for the two officers.

Although it's not open to the public due to space constraints, public gatherings to view the funeral will be held at the Grant-Harvey Centre and the Hope City Church.

The public is also encouraged to line the streets of Fredericton for a parade procession made up of police officers and first responders that will precede the funeral.

Meanwhile, an obituary published by Carleton Funeral Home in Jacksonville, N.B., said Wright graduated from Canterbury High School in 2003 and from New Brunswick Community College with a diploma in medical office administration in 2008.

The 32-year-old woman had previously worked on a tree farm, in catering and in an office before embarking on a career as a home support worker.

An obituary for Robichaud said he is survived by a wife and three children, and there will be no visitation or funeral, in keeping with his wishes.

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

Police have said Wright and Robichaud, who had just begun a romantic relationship, were shot first in the parking lot outside Robichaud's apartment building, and the two officers were shot when they responded.

Fredericton police spokeswoman Alycia Bartlett said an update on the case is not expected before Saturday's funeral.

RCMP in New Brunswick are assisting the municipal police force in the homicide investigation, but Corp. Jullie Rogers-Marsh said all updates will come from Fredericton police.