The 35-year-old Mountie who was killed Tuesday night when he pulled over to help change a flat tire on the Trans-Canada Highway near Memramcook, N.B., had a history of going above and beyond to help others, said the commanding officer of the Nova Scotia RCMP.

Const. Francis Deschenes was hailed as a hero in 2008 for saving a 26-year-old woman whose car was stopped on railroad tracks near Truro, N.S., as a CN freight train sped toward it, said Assistant Commissioner Brian Brennan.

Deschenes used his cruiser to push the car off the tracks, with only seconds to spare before the ongoing train would have smashed into the car and possibly derailed.

"That's just one demonstration of his dedication and commitment," Brennan told reporters during a news conference Wednesday at the Amherst detachment where Deschenes, a newlywed, worked in traffic services.

The northern New Brunswick native and 12-year veteran of the national police force was also a 2013 recipient of the Queen's Diamond Jubilee medal, which honours "significant contributions and achievements by Canadians."

Brennan did not know Deschenes personally, but said based on conversations with his family and friends, "he was extremely dedicated to the RCMP.

"He loved what he did."

Nova Scotia RCMP Assistant Commissioner Brian Brennan

Nova Scotia RCMP Assistant Commissioner Brian Brennan said all members of the RCMP are feeling the loss of Const. Francis Deschenes. (CBC)

Deschenes's actions on Tuesday, stopping to help two people in an SUV change a tire, "speaks to the core of what policing should be — involved in your community, looking out for people, taking the time to do those small things that would go a long way," said Brennan.

His work as a traffic reconstructionist trained to investigate collisions and determine causes, as a member of the Special Tactical Operations/Tact Troop, and as a former member of the Musical Ride "speaks to his dedication and his willingness to go the extra mile and do the best he can for everybody," he said.

Const. Francis Deschenes saved a life rescuing a car from railroad tracks in 20080:40

The preliminary investigation by the New Brunswick RCMP indicates a utility van collided with the marked police car and the SUV in the eastbound lanes at the 480-kilometre mark shortly after 6 p.m. AT.

Deschenes died at the scene. The two people from the SUV were taken to the hospital and later released.

The driver of the van was also treated in hospital and taken into police custody. No charges have been laid.

'Unimaginable tragedy'

Brennan said he could not provide many details about the circumstances of Deschenes' death, given the active criminal investigation.

But he described the loss as a "tragic day for the Nova Scotia RCMP and our entire RCMP family."

"It is extremely challenging to describe what it feels like when we lose one of our own. In the RCMP, we are a family and every employee in Nova Scotia and across the country is impacted by the loss of Francis … Frank as he was better known."

Const. Francis Deschenes, book of condolences

Members of the public are being encouraged to sign books of condolences set up at the RCMP detachment in Amherst and at the headquarters in Halifax. (Tori Weldon/CBC)

Brennan said he met with Deschenes' wife and family members. "They are dealing with unimaginable tragedy, and I ask that they be given the privacy and respect they deserve as they grieve the loss of their husband, son, brother and friend."

The RCMP's focus in the coming days will be on the continued support for Deschenes' family, friends and colleagues, he said.

"This is going to be a tough road ahead, and we have to take care of each other and ensure people are receiving the care and support they require."

Amherst flag lowered Sept. 13, 2017

Flags outside the Amherst RCMP detachment were at half-mast on Wednesday. (Tori Weldon/CBC)

Outside the Amherst RCMP detachment, flags were at half-mast on Wednesday afternoon.

An arrangement of red and white carnations was also sitting by the sign. The attached card says, "Missing you like crazy, RIP our friend."

A book of condolences was also set up inside the Amherst detachment, as well as headquarters in Halifax to honour Deschenes, who started his career at the Stewiacke, N.S., detachment and Bible Hill before joining the Musical Ride and later returning to Amherst.

Prime Minister Justin Trudeau tweeted his "deep condolences" to the family and friends of the officer "killed in the line of duty."

"We mourn with his fellow RCMP," he wrote.

Federal Public Safety Minister Ralph Goodale issued a statement.

"The death of a police officer is a stark reminder of the sacrifices and bravery of our police women and men who put themselves in harm's way each and every day to keep Canadians safe and secure," he said.

Amherst RCMP flowers

A flower arrangement was sitting beside the Amherst RCMP detachment sign on Wednesday. (Tori Weldon/CBC)

Amherst Police Department Chief Ian Naylor said officers sometimes forget their jobs "can be very dangerous."

"We get used to it, that's our norm," he said. "The things that we deal with on a regular basis, if the average person dealt with it, you know, it would be a traumatic event in their life."

"When this type of thing happens, it reminds all police officers how dangerous our jobs can be and every time we put that uniform on we potentially can be in a dangerous situation and our lives are at risk."

'You're just kind of left with an empty and helpless feeling.' - Ian Naylor, Amherst police chief

Naylor said his department has a close working relationship with the local RCMP and some of his officers knew Deschenes, both professionally and personally.

"It numbs you," he said. "These types of things happen and you're just kind of left with an empty and helpless feeling."

Naylor planned to brief his officers on Wednesday afternoon and let them know the department has reached out to the RCMP, expressing "sympathies and prayers."

"We certainly let them know if there's anything we can do to help them, whether it be operationally or whatever … that we are there for them," he said. "They've helped us [when] we've had difficult situations in the past and we'll do the same for them."

Emergency responders and citizens across the Maritimes expressed sadness and anger about the officer's death in hundreds of posts on social media.

"Our thoughts and prayers are with the RCMP officer, his family and colleagues during this difficult time. Such a tragic preventable loss," the Kennebecasis Regional Police Force's traffic division tweeted.

"Our thoughts are with our RCMP friends and families who lost one of their own yesterday. So sad," the Fredericton Firefighters Association, Local 1053, tweeted.

"The public is sharing the heartache and the sorrow," Chris N Nancy Oulton wrote on Facebook.

Christopher Haworth posted that "all jurisdictions need to re-educate and emphasize the importance of slowing down and moving over for emergency vehicles."

In New Brunswick, the so-called move over law passed in 2013 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.

Anyone who violates the provisions of the provincial Motor Vehicle Act faces a fine of $292.50 and the loss of three points off of their driver's licence.

The law was passed in 2013, just a few months after a Sûreté du Québec officer was struck and killed by a passing vehicle in the Laurentians.

With files from Tori Weldon and Preston Mulligan