Investigators with the Transportation Safety Board are carefully sifting through the wreckage of a helicopter that crashed in B.C., as residents mourn the deaths of the pilot, two passengers and a pedestrian who was killed on the ground.

Damien Lawson, a spokesperson for the TSB, said officials are also questioning witnesses to get a better sense of what caused the tragedy.

"It's always a challenge when you're talking to people well after the event, 24 hours after the event, because their information becomes tainted by what they see on the media and from talking to other people," Lawson told reporters Wednesday.

The helicopter went down Tuesday afternoon in Cranbrook, a town of 18,000 people about four hours west of Calgary in the Kootenay mountains.

The pilot, two passengers who were both BC Hydro employees, and a pedestrian were killed when the aircraft dropped from the air, slammed into the ground and burst into flames.

The RCMP has released the names of three of the four victims. They are:

  • Helicopter pilot Edward William Kyle Heeb, 57
  • BC Hydro employee Dirk Bentley Rozenboom, 45
  • BC Hydro employee Robert William Lehmann, 37

Reports identify the pedestrian as Isaiah Oiteno, a 23-year-old, 6 foot 9 international student from Kenya. He had been living in Cranbrook for two years while studying business at the local college.

Heeb was a former television reporter, who once worked in Vancouver in the 1980s with CKVU -- now known as CityTV. He had 17 years of helicopter piloting experience before the crash.

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All the victims lived in the Cranbrook area, said CTV Calgary's Chris Epp.

He said several witnesses reported seeing the pilot try to steer the helicopter away from people's homes.

The chopper crashed on the street between an apartment building and a row of houses.

"So there are a lot of people living in this area, a lot of people home at the time of the crash. The pilot seemed to take the chopper down in the street, in the middle, to do the least damage possible," Epp told CTV's Canada AM on Wednesday.

However, there are still many unanswered questions about the crash. Transportation Safety Board officials only had several hours to investigate before darkness fell Tuesday night.

"The chopper wreckage is still in the street but it is covered by a tent," Epps said. "That was done overnight to make sure nothing disturbed the evidence overnight and they'll take another crack at it at first light today," he said.

"At this point they're relying a lot on what witnesses tell them but they say it could be weeks or perhaps months before they know the actual cause."

Witnesses gave varying accounts of what transpired in the few minutes prior to the crash.

Elmer Bautz, who lives on the street where the chopper crashed, said he watched the crash happen.

"I thought at first it hit a tree, like the propeller hit a tree. But it didn't appear that it did. Anyway I saw it come down from about 300 feet almost at a 45-degree angle and whomp, she hit the sidewalk right across the street from me," he told Canada AM.

Bautz said the helicopter was "sort of fluttering" before it began to descend, and he speculated that it may have had a fuel problem.

Bautz said the pedestrian was just walking on the sidewalk and had no chance to escape the danger.

Richard Fairchild, who also saw the crash, told CTV Newsnet on Tuesday that the chopper had barely cleared a large pine tree and "within a second-and-a-half it crashed right in front of us -- literally in front of our window."

"It didn't crash at a high speed. The pilot had been trying to control it, but the motor was out at that point and he fell the last 15 feet."

Bill Yearwood of the Transportation Safety Board says the craft that went down is a Bell helicopter Model 206. He told The Canadian Press Tuesday that three TSB investigators had been dispatched to scene.

"Of course they will be trying to see first if there was any catastrophic failure in the aircraft that we might need to look and see if there's other similar aircraft at risk," said Yearwood.

"That's their first goal. The wreckage will be examined on site and then transported somewhere where we can have a closer look at it."

The chopper was hired by BC Hydro and was owned by Big Horn Helicopters, a Cranbrook company. BC Hydro CEO Bob Elton said that his employees were in the chopper on routine line patrol when it crashed.

With files from CTV British Columbia