RCMP in B.C. have released the name of the officer killed when his unmarked cruiser collided with a semi-tractor in Surrey, B.C., early Tuesday morning.

Const. Adrian Oliver, 28, was at the end of his shift when he was killed in the crash at the intersection of 64th Avenue and 148th Street around 5 a.m. PT.

The cause of the collision remains unclear. Vancouver police have taken over the investigation, and traffic on 64th Avenue between 144th and 152nd streets was shut down following the crash.

The truck, which belongs to Heaven Transport, was not hauling a trailer at the time, and police said the driver was not injured in the crash. He was described as an experienced driver who had been with the company since August.

Police said the death was the first on-duty fatality for the Surrey detachment since 1975.

Oliver joined the force in 2008 and arrived at the Surrey branch in 2009, officers said at a sombre news conference on Tuesday morning.

He was the second generation of his family to serve with the RCMP. Oliver's father is posted in Ottawa and his brother is stationed in the Lower Mainland of B.C. Family members are flying out to B.C., officers said.

Officer pinned in vehicle

Witnesses say paramedics arrived on the scene and found the officer unconscious, pinned in the wreckage of the grey unmarked cruiser.

Darryl Walker, the operations manager of recycling company Emterra Environmental, located near the same intersection as the crash site, said it was clear from the tangled wreck of the police cruiser he saw that the officer could not have survived.

"The engine was sticking right out," he said. "It was a mess."

The unmarked RCMP cruiser was crushed in the collision with a semi-tractor. (CBC)

About a dozen Mounties were gathered at the scene when he arrived at work, Walker said.

At least eight blocks were closed in one direction and four in another, snarling rush-hour traffic in the industrial area, Walker said.

"Everyone is upset to hear a member of the RCMP has died in this way. They have a hard enough job as it is."

Leaders offer condolences

The head of the Surrey detachment, Chief Supt. Bill Fordy, said it was a tragic day for the force.

"Const. Adrian Oliver was 28 years old and has served his entire 3½ year career as a member of the Surrey RCMP. He was an outstanding police officer, with a great attitude and commitment to serve others," said Fordy.

In Ottawa, RCMP Commissioner Bob Paulson said he was upset by the loss of an officer and a family friend.

Adrian Oliver, 28, joined the force in 2008 and arrived at the Surrey, B.C., branch in 2009. He was the second generation of his family to serve with the RCMP. (Steve Lus/CBC)

"My initial reaction was to cry, because I've met him. He's a son of a senior officer here at headquarters who's a friend, and just an incredibly tragic loss of life, and the third person who's died under my watch, and I find that very difficult," said Paulson.

"They care about the Canadian way of life, they carry the responsibility of the history of this organization and this country in their pocket every day. And you know, when we lose one of them, it's very, very difficult," he said.

B.C.'s Justice Minister Shirley Bond issued a statement of condolence.

"I was very sorry to learn of Const. Oliver's tragic death. We know the loss of any officer is a tragedy and our community is diminished today because of it," said Bond.

Federal Public Safety Minister Vic Toews also extended his condolences.

"His family has a long tradition of service to the RCMP and this loss will be felt by many. This is a very sad day for all Canadians. The death of a police officer in the line of duty reminds us of the devotion and sacrifice of those who serve each day to keep us safe."

With files from The Canadian Press