A 35-year-old Mountie who pulled over to help two people in an SUV change a tire Tuesday evening was killed when a utility van collided with his cruiser.

Const. Francis (Frank) Deschenes, a northern New Brunswick native, died at the scene on Highway 2 near Memramcook, N.B.

The 12-year veteran, who worked for the national police force in Amherst, N.S., was on duty with traffic services at the time, said RCMP. He was in uniform and in a marked police vehicle.

The two people in the SUV who had stopped at the roadside because of the flat tire were taken to hospital and later released, said RCMP.

The driver of the van was also taken to hospital, where he was treated before being taken into custody.

New Brunswick RCMP Cpl. Jullie Rogers-Marsh said she didn't know the extent of their injuries.

Our deepest sympathies go out to his whole family and to the whole RCMP family for what happened last night. - Michel Gaudet , mayor of Memramcook

It's too soon to say if charges will be laid, Nova Scotia RCMP Assistant Commissioner Brian Brennan said during a news conference in Amherst on Wednesday afternoon.

The collision will be investigated by New Brunswick RCMP like any other motor vehicle accident, he said.

Brennan could not say if the lights on Deschenes' car were activated or whether Deschenes was inside or outside the car at the time, but he died at the scene.

It's unclear why Deschenes was in New Brunswick, but Brennan said it's "not unusual," given how close Amherst is to the border.

The collision happened at the 480-kilometre mark in the eastbound lanes shortly after 6 p.m. AT.

Traffic was diverted all night.

Traffic was diverted overnight after the crash that killed an RCMP officer. The highway opened about 8:30 a.m. Wednesday. (Wade Perry)

Police are still trying to figure out how the fatal crash happened, said Rogers-Marsh.

"There could be more details that come out later."

Video gathered at the scene showed a van and an SUV, but the RCMP cruiser appeared to bear the brunt of the impact. This was corroborated by a witness.

'It's a sad day'

Memramcook Mayor Michel Gaudet said the community is in disbelief following the Mountie's death, calling it a "sad day" for the area.

"Any time you have a death of anybody, let alone a police officer, it's always very tragic," said Gaudet.

"Our deepest sympathies go out to his whole family and to the whole RCMP family for what happened last night."

An RCMP cruiser was struck at the side of the eastbound lanes of Highway 2 near Memramcook Tuesday night. (Pierre Fournier/CBC)

Mike Spearns, a former traffic officer with Halifax police, said there are always dangers when police pull over.

"There's more danger in an officer doing traffic stops, road checks, assisting people on the side of the road than there are of armed robberies, or drug dealers, or responding to known dangerous situations," he said.

In 2013, New Brunswick passed the "move over" law.

The law requires drivers to slow down and, where possible, move into the left lane when emergency vehicles are pulled off the road with their lights flashing.

Highway 2 near Memramcook at km480 eastbound lane is now open. —@RCMPNB

Spearns said officers are trained in proper traffic procedures and specifically look for areas where they can stop a vehicle safely and move them far enough off the roadway, but accidents can be caused through inattentive driving.

"Unfortunately … emergency responders are exposed to those risks," he said. "You can take all the necessary precautions and still, things can go off the rails."

Highway 2 near Memramcook, N.B. has been closed as RCMP and other emergency responders continue to work at the scene of a collision. 0:56

RCMP said the road was closed while emergency crews worked at the scene and was reopened around 8:30 a.m. Wednesday.