Harrowing video has emerged of the early morning police standoff that followed the deaths of four people, including two police officers, in Canada.

One suspect is in custody with serious injuries sustained following a shootout with police, but authorities have revealed nothing about him except that he is a 48-year-old man from Fredericton, New Brunswick.

Fredericton is a city of roughly 58,000 about 75 miles from the Maine border.

The incident began when police in Fredericton responded to a call of shots fired in a residential neighborhood at around 7.10am on Friday, finding an adult male and an adult female dead at the scene.

The first two constables on the scene, 45-year-old Lawrence Robert Costello and 43-year-old Sarah Mae Burns, were also killed by the shooter.

Costello was a 20-year veteran of the department and father of four, and Burns had been on the force for two years, and was a mother of three.

A massive police response ensued, with a standoff unfolding in an apartment complex where the initial shootings took place.

The first two constables on the scene, 45-year-old Lawrence Robb Costello (left) and 43-year-old Sarah Mae Burns (right), were killed by a shooter Friday morning in Fredericton

Police and RCMP officers rush to respond to a shooting in Fredericton, New Brunswick on Friday. Fredericton police say two officers were among four people who died in the shooting

Paramedics are seen loading casualties in the shooting. Multiple people were injured and hospitalized, including the suspect who was seriously wounded, police say

Newly obtained video of the police standoff shows cops in an armored vehicle firing tear gas canisters into the upper-floor window of an apartment building on the 200 block of Brookside Drive.

'They're gassing him out boys!' the person filming from an adjacent building shouts nervously.

The suspect was taken into custody by 9.45am.

By 11am local time, police confirmed that there was no further threat to the public, and lifted a lockdown on the area as the investigation continues.

Multiple people were injured in the shooting and are currently being treated at Dr. Everett Chalmers Regional Hospital, according to parent company Horizon Health.

There was a heavy police presence at the hospital on Friday and officials asked area residents to avoid using the emergency room except for serious emergencies to allow doctors to focus on treating the wounded.

The apartment complex where the shooting took place is seen as police investigate on Friday

Provincial police set up a mobile command post at the apartments where they shooting took place as they process evidence and investigate the deadly events

Police said Brookside Drive between Main Street and Ring Road will remain closed 'for the foreseeable future' to work the investigation.

David MacCoubrey, who lives on Brookside Drive, said that he woke up in his apartment at around 7am to the sound of three gunshots about 30 feet away from his bed.

MacCoubrey said more than 15 other gunshots were subsequently fired between that time and around 8.30am.

He says his apartment complex has four buildings in a square, and it sounded like the shots were coming from the middle of the complex.

MacCoubrey said police have been searching the complex and he has been sitting on the floor of his home away from windows.

'It's not something that happens here regularly,' he said.

A police K9 unit is seen as part of the massive emergency response to the shooting on Friday

The shooting is believed to have happened in or around the low-rise brick apartment buildings seen in the background of the photo above, as police secure the scene

Travis Hrubeniuk said his fiancee had just left for work at around 7.45am when he began hearing a steady stream of sirens.

Hrubeniuk said residents were advised to stay inside with their doors locked. The quiet residential neighborhood, which has houses, grocery stores, a church and an elementary school, is the last place Hrubeniuk said he expected to encounter a dangerous situation.

'This is the first time I've even heard of any serious crime or violent crime in this city,' he said.

Another area resident, Robert DiDiodato, told the CBC that he heard sounds like a 'firecracker' at around 7am.

'With the tempo, it might've been a gunshot,' he said. 'It was sort of like a pop, pop, pop, pop.'

He heard similar sounds about five minutes later, near his home, he said.

Police are seen manning a cordon as the investigation proceeds into the deadly shooting

Local police and RCMP officers are seen maintaining a security cordon at the shooting scene

Emergency vehicles are seen at the Brookside Drive area in Fredericton, Canada on Friday

At about 9.45am, police said that they had one suspect in custody. But officials warned that the incident was 'still active' and urged residents to stay inside and lock their doors.

'Please stay away from the area. Stay inside, lock your doors. Do not disclose police locations on [social media]. Wait for updates from police,' the Fredericton Fire Department said on Twitter.

The lockdown was lifted at 11am. 'We can confirm that there is no further threat to the public, and lockdowns are not required at this time,' police said in a statement.

'Police still have the crime scene contained, and will be working the investigation for some time.'

The RCMP will be taking responsibility for the homicide investigation, while the provincial Serious Incident Response Team will handle the investigation into any police officer related shooting.

Later on Friday, Canadian Prime Minister Justin Trudeau offered his condolences on Twitter.

'Awful news coming out of Fredericton. My heart goes out to everyone affected by this morning’s shooting. We’re following the situation closely,' Trudeau wrote.

Fredericton Police Chief Leanne Fitch addresses a news conference in Fredericton, New Brunswick, Canada, on Friday after two officers and two civilians were shot dead

Flowers are placed outside the police station in Fredericton, New Brunswick Canada on Friday. Two city police officers were among four people who died in a shooting in a residential area

In 2014, another mass shooting in New Brunswick led to the deaths of three Royal Canadian Mounted Police officers and the wounding of two more in Moncton.

At the time, the incident was one of the worst of its kind in Canada, where gun laws are stricter than they are in the United States and deadly attacks on police are rare.

However, in recent years, Canada has seen a dramatic uptick in high-profile shootings.

Last month, a gunman walked down a busy Toronto street, killing two people and wounding 13 before turning his gun on himself.

On Thursday, Ontario pledged more money for police and to keep suspects behind bars while they await trial on gun crimes charges, as the Canadian province grapples with rising shootings involving domestically obtained weapons.