A picture is slowly emerging of the three RCMP officers slain in Moncton, N.B., as their colleagues continue to scour the area looking for the shooter.

One of the officers, Const. Dave Ross, was originally from Victoriaville, Que., CBC News has confirmed.

His mother-in-law, who asked not to be named, said Ross and his wife have a 19-month-old child and are expecting another in September.

Const. David Ross, pictured here with his wife on his wedding day, was one of three Mounties killed in Moncton, N.B., on Wednesday night. (Courtesy of family/Facebook)

She said Ross had lived in New Brunswick for seven years after graduating from police academy and considered himself a New Brunswicker.

She said this is "the most horrifying, difficult experience" of their lives.

One of the officers had three children, according to the RCMP.

"Our top priority is to locate and arrest the suspect, as well as to resolve the situation as soon as possible," Cpl. Chantal Farrah said during a news conference on the manhunt for Justin Bourque, 24.

Two injured officers underwent surgery on Thursday. One has been released, said Farrah, while the other is in stable condition with non-life-threatening injuries.

Search continues

For the second night in a row, police in Moncton, N.B., are asking residents to turn on their outdoor lights to aid police searching.

"The safety of the residents as well as that of our police officers involved in this operation is extremely important to us."

Despite the uncertainty and fear surrounding the southeastern New Brunswick city, Moncton Mayor George LeBlanc says there's a "desire to pull together."

“There’s a sense of apprehension to a degree and a desire to see this person brought in and apprehended. I think there’s a sense of sadness over the loss of life,” LeBlanc told CBC News on Thursday night. "Finally I think there’s a hope to move forward and begin the healing process.”

An RCMP officer rests his head at a roadblock in Moncton, N.B. on Thursday, June 5, 2014. Three RCMP officers were killed and two injured by a gunman wearing military camouflage and wielding two guns on Wednesday. Police have identified a suspect as 24-year-old Justin Bourque of Moncton. (Canadian Press)

People who live in the Moncton North Zone, where the search is focused, are still being urged to stay locked inside their homes for their own safety and to not share details about police operations on social media.

Citizens are asked to immediately call 911 if they spot Bourque, said Farrah.

RCMP have said they believe Bourque is within an area bounded by Berry Mills Road, Killam Drive, Mountain Road and Evergreen Drive in the Pinehurst subdivision of Moncton.

He is considered "armed and dangerous," and is equipped with high-powered guns, knives and a crossbow. He was not previously known to police.

Anyone who has other information about the gunman should call 506-857-2400, Farrah said.

Canada grieves

The situation has sparked an outpouring of messages of support and condolences from across the country.

The hashtag #PrayforMoncton was trending worldwide on social media and flags were lowered to half-mast in many locations, including Parliament Hill in Ottawa.

A weapon is passed to an Emergency Response Team member on the roof of a house in Moncton, N.B., on Thursday during the manhunt. (Canadian Press)

The House of Commons also observed a moment of silence to honour the slain officers on Thursday, just before question period got underway.

As many try to wrap their heads around the events unfolding in Moncton, so are those who know the accused killer.

Trevor Finck said he’s been in shock since discovering Bourque, once a close friend, is the man police are after.

“If you knew him, it just didn’t seem like his personality. He was a very calm, laid-back kind of guy. But at the same time it was still within the realm of possibility with him. It seemed like he was starting to believe more conspiracy theories,” he told CBC’s As it Happens.

Finck said he last saw Bourque about a month ago.

Dramatic search

Most of the city has been under a virtual lockdown since Wednesday night.

Many people hid in their basements or closets overnight and much of the day, unable to sleep, knowing a gunman was on the loose nearby.

Earlier in the day, RCMP officers and three armoured trucks had the rooming house, located in a busy commercial area, surrounded for several hours.

Officers entered a rooming home in the city's north end at about 3 p.m. AT, as dozens of people watched from behind police blockades.

But most of the officers cleared the scene with no sign of the gunman.

A map from RCMP shows the search area in Moncton. (RCMP)

Police also searched a nearby private home to no avail.

Some of them were crouched behind their vehicles, which blocked the street, while others were wearing protective masks and carrying automatic weapons.

There were canine units, at least three armoured trucks and reported sightings of snipers.

There had also been at least one unfounded report of Bourque being in the Oromocto area, which is roughly 150 kilometres west of Moncton and 20 kilometres east of Fredericton.

Schools were secured as police searched the area.

Codiac RCMP Supt. Marlene Snowman told a news conference that police spotted the suspect three times Thursday morning — in the area near Gorge and Mountain roads, and two other times. The police were unable to apprehend him.

Roger Brown​, RCMP assistant commissioner, also told the news conference that "there is no way to describe the level of hurt" inside the police force.

"This is working through your worst nightmare," Brown said.

We are professionals and we have a job to do right now. We will have time to grieve after. - Const. Damien Theriault

"We need to focus back on the families. We have one of our members with three children. And you know, these are, these are real-life situations," he said.

Brown promised to keep the public informed of any developments in the Moncton manhunt.

The #PrayforMoncton hashtag, which was trending worldwide, was also posted outside this closed Moncton business on Mountain Road on Thursday. (Kate Letterick/CBC)

"We will come back [to speak to the media] and once this person is apprehended, and he will be, then I think we, collective, I know from a policing perspective, we will breathe a sigh of relief," Brown said.

"But at this point in time, that's not the situation right now."

He said Moncton is still gripped by a "very, very dangerous situation."

The hunt started after police received a call at 7:20 p.m. AT Wednesday about a man wearing camouflage and carrying guns.

RCMP searched every vehicle in the area on Wednesday night, said CBC reporter Melissa Oakley.

Additional police resources from across New Brunswick and other provinces are in Moncton to assist RCMP in the manhunt.

RCMP Const. Damien Theriault told CBC's Information Morning in Moncton he "lost three friends."

"And now we need to pull together and locate this individual as quickly as possible to ensure everyone's safety," said Theriault, who was clearly emotional.

"We are professionals and we have a job to do right now. We will have time to grieve after."

Oh my God, there he is with camouflage and the headband and a gun, and it looked like a bow he had with him. And I mean he was just through our backyard. —Joan MacAlpine-Stiles, Moncton resident and witness

'We're scared, obviously'

CBC reporter Stephen Puddicombe said on Thursday he has spoken to Moncton residents who said the shooter was targeting people with uniforms.

“He laid in ambush for the police when the calls were made and shot them from an ambush position. He saw and spoke to several civilians and did not shoot at them at all. He was out to get people in uniforms,” he said.

The shooting has rattled people in Moncton's north end.

Joan MacAlpine-Stiles said she saw the gunman when she went to open a window.

"It was really warm in the house, so we opened up the windows in the family room and there he was going across through the back with this rifle on his shoulder," she said.

A youth rides his bike past a trailer that is the Moncton residence of the suspect, 24-year-old Justin Bourque. (The Canadian Press)

"I said, 'Oh my God, there he is with camouflage and the headband and a gun, and it looked like a bow he had with him. And I mean he was just through our backyard.'"

Vanessa Bernatchez posted a video on Facebook from the moment the gunman opened fire, apparently killing an officer.

Watching from inside her living room with several others, Bernatchez said it appears the Mountie didn’t see the shooter until the gunfire erupted.

“It was too late, he went down. We knew it was over,” Bernatchez told CBC News Network.

On the video, a man describes what’s happening outside.

“He shot him … he shot a cop,” he said.

“Oh my God,” Bernatchez screams. “Call 911.”

The video ends with her racing to the phone. Police and a tactical team arrived on the scene soon after, she said.

Will Njoku said he was emptying his dishwasher and putting his young children to bed just before 8 p.m. when he heard popping sounds.

"Within 30 seconds I heard sirens," he said.

RCMP officers gather early Thursday morning as the search for Justin Bourque continues following the shooting deaths of three RCMP officers and the wounding of two others in Moncton, N.B. (CBC) Njoku said he heard five more shots after the sirens.

"We’re scared, obviously. We’re more terrified for the people who this shooter is basically in their backyard. I can picture these people’s houses," he said.

When the news broke that there was a shooter on the loose, Njoku said, he went out on his street to warn his neighbours.

"I felt pretty dumb. But there was people going down there. I just know my neighbourhood. It’s just kid city," he said.