Lorna Weafer, a 36-year-old instrument technician, has been identified as the worker killed at a Suncor oilsands site north of Fort McMurray, Alta. on Wednesday night.

Weafer was attacked by a large, male black bear around 2 p.m. MT.

Mike Ewald, an investigator with Alberta Fish and Wildlife, said Weafer was on her way back to work from a washroom when the bear attacked.

Those who saw the attack said it happened quickly. No one saw where the bear came from.

Ewald said Weafer’s co-workers tried to scare the bear off using fire extinguishers, a water cannon and air horn – “All the general things that should scare it off,” Ewald noted.

Employees told him the bear would shy off for a bit, but kept coming back – eventually killing the woman.

"This bear was very determined,” Ewald said, adding that the attack lasted about an hour.

Scott Doherty, a spokesman for the union Unifor, told The Canadian Press that Weafer was working in a team with six others at the time of the attack. Doherty said the union does not believe the workers were carrying bear spray.

RCMP shot and killed an adult black bear that was spotted nearby as soon as they arrived.

Investigation ongoing

Occupational Health and Safety, as well as Alberta Fish and Wildlife, continue to investigate the incident, trying to find out how Weafer's death could have been prevented.

Investigators have closed off a 200-square-metre area around the site of the attack and have set up several live bear traps in the vicinity.

After speaking to witnesses and conducting a DNA analysis, Ewald confirmed that the bear that was shot and killed by RCMP was the same one that killed Weafer. 

A second bear was trapped, but Ewald said it has been let go. 

Based on the preliminary investigation, Ewald said this appears to be a predatory bear attack, noting there was nothing around that would have attracted the bear and that the attack was not provoked “in any way.”

“Predatory attacks are quite rare in Alberta,” he said. “The last fatal black bear mauling in Alberta was somewhere around 1991 in Slave Lake.”

In that incident, a 12-year-old boy was killed at a campground. Prior to that, in 1980, two oil rig workers were killed by a black bear near Zama Lake, Alta.

Attacks by grizzly bears are more common, he added.

Workers receive regular wildlife training

Safety officials said companies working in the area have protocols in place to avoid such attacks.

Doherty said the union plans to conduct a full review into the incident, which is the third workplace fatality in four months at the Suncor site.

“If there needs to be a revision or some additional procedures and policies in place to ensure the safety of workers from wildlife attacks, we are definitely going to do that."

Suncor spokeswoman Sneh Seetal said workers undergo regular training on how to interact with wildlife, and are told to report any sightings.

Seetal said employees who work in the bush carry bear spray, but staff in busy industrial areas such as where Weafer was attacked usually only carry air horns to scare away aggressive wildlife.

However, Ewald told CBC News that, in this case, additional wildlife training would not have helped.

“This was one of those events … yeah, they’re extremely rare,” he said, at a loss for words.

“With wildlife incidents like this ... it also reminds that’s exactly what they are – wildlife – and not predictable and there’s no cookie cutter solution for dealing with human-wildlife conflict.”

Most fatal attacks are predatory

Bear behaviour expert Stephen Herrero with the University of Calgary agrees with Ewald on the rarity of fatal black bear attacks.

However, he added, serious attacks tend to involve male bears and are "predatory in nature.”

"We've studied the nature of fatal black bear attacks over the last 110 years, 90 per cent of those fatal attacks were carried out by male black bears."

"Something in the bear says 'Maybe this is something I can capture kill and eat,'" he added.

Herrero said the best way to deter an attack is to use bear spray.

"They should always carry accessible bear spray with them," said Herrero. "Our studies have shown bear spray to be 80 to 90 per cent effective in all sorts of different circumstances with black bears and grizzly bears."

Alberta trapper and wildlife expert Bill Abercrombie suggests that the late spring weather may have been a factor in making the bear so aggressive.

Adult black bears, which typically weigh about 200 kilograms, have been known to attack humans for food and this is the time of year they will travel to find something to eat.

“This spring we’re running a little late in terms of the frost coming out of the ground and the forage for the bears being available in a timely manner for them when they’re out of their dens,” Abercrombie said.

“I think the bears might be a little hungrier this spring.”

Black bears have been a problem in northeastern Alberta in the past. In 2011, wildlife officers destroyed 145 black bears, including animals attracted to garbage near work camps.

With files from The Canadian Press