A chopper carrying four people plunged into the Kitsault River near Alice Arm, B.C., around 7 a.m. Wednesday. (CBC)

The RCMP have confirmed four people on board a chartered helicopter died after it crashed into a river about 150 kilometres northeast of Prince Rupert, B.C., Wednesday morning.

"All four of the helicopter's occupants have now been located and are confirmed deceased," Prince Rupert RCMP Const. Krista Vrolyk said in a news release.

A spokesman for the Canadian Coast Guard told CBC News the chopper carrying four people plunged into the Kitsault River near Alice Arm around 7 a.m.

Dan Bate said a Canadian Coast Guard helicopter with RCMP officers and a coroner on board was en route to the site.

The crash site is accessible by air and water only, and the Transportation Safety Board of Canada has begun an investigation into the cause of the crash, Vrolyk said.

Dave Zall, president of Prism Helicopters, which has its headquarters in the Vancouver suburb of Pitt Meadows, told CBC News the chopper belonged to his company.

He said there were no survivors and "that's all we know right now."

"It's a sad day for all of us here, and nobody likes to see this happen," Zall said.

3 crashes in B.C. in a week

This is the third fatal aircraft crash in B.C. in less than a week.

On Monday, an ultralight aircraft crashed into Moose Lake in Mount Robson Provincial Park in eastern B.C.

An RCMP dive team searched the lake to a depth of 40 metres on Tuesday, but members were unable to find any trace of the aircraft or pilot. The dive team went back into the water on Wednesday with sonar equipment to help in the search.

On Sunday, a plane went down on Vancouver Island, killing five people. The Grumman Goose amphibious aircraft, chartered from Pacific Coastal Airlines and carrying seven people, crashed shortly after taking off from Port Hardy, B.C., at about 7 a.m. PT Sunday.

Federal Transport Minister Lawrence Cannon said it's been a tragic week for aviation in B.C. His ministry will co-operate fully with the Transportation Safety Board investigations and any safety deficiencies will be addressed, he said.

Nearly two years ago, three people died in a helicopter crash near the site of Wednesday's crash. In September 2006, a Bell-206 owned by Quantum Helicopters of Terrace, B.C., crashed in a remote marshy area near Alice Arm, about 120 kilometres northwest of Terrace.

With files from the Canadian Press