Clifton Purvis is the executive director of ASIRT. (CBC)One of the vehicles in a fiery double-fatal crash that occurred after an Alberta RCMP chase was stolen, according to the provincial agency investigating the incident.

"It was not initially known why the operator of the subject vehicle refused to stop for police," said Clifton Purvis, executive director of he Alberta Serious Incident Response Team, ASIRT. "It has since been determined that the operator of that vehicle was driving a stolen vehicle."

The crash killed two men, 21 and 30, on Highway 16 just outside Hinton.

The younger man was the driver of a stolen minivan that was being pursued by police Thursday afternoon. The 30-year-old was driving a pickup truck also involved in the head-on crash.

ASIRT will investigate whether the actions of the RCMP officers involved in the chase were justified, Purvis said.

"We'll interview all the witnesses that come forward in relation to this incident. We'll interview the police officers that are involved, dispatchers that may have been providing assistance to the police officers involved," he said.

"Both police vehicles were equipped with … video camera recording equipment. We've secured that evidence, so we have a very clear visual of what the police were looking at when they were involved in the situation."

The names of the victims have not yet been released.

Minivan first seen near Jasper

An off-duty RCMP officer first reported the minivan being driven in an erratic manner near Jasper, police said.

The crash occurred along this stretch of Highway 16 outside Hinton, Alta. (CBC)Jasper RCMP initially tried to stop the vehicle near the east Jasper park gates on Highway 16 at about 4:50 p.m., but the eastbound minivan failed to stop, according to the RCMP.

The police did not pursue the vehicle at that point, and instead, notified RCMP in Hinton it was headed their way, Purvis said.

The minivan then passed two RCMP cars as it entered Hinton. The minivan failed to stop when signalled by police and began to accelerate at a high speed through the town, travelling eastbound in the westbound lanes of Highway 16, according to police.

Shortly after 5 p.m., the minivan crested a hill and struck a pickup truck, which burst into flames on impact. Neither driver survived the head-on collision. Both men were alone in their vehicles.

Van was speeding down highway: witnesses

Eyewitnesses in Hinton said they saw the minivan on Highway 16 moments before the crash.

"The van was speeding, probably over 100 kilometres an hour," said Corrinna Mack, who was driving to the mall at the time. "I saw the red light ... I couldn't believe it wasn't stopping or slowing down."

Donald Wolf said he saw the van while he was standing outside the restaurant where he works.

"We saw the van go flying by on the wrong side of the road, with the three cops right behind it," Wolf said. "And an hour later, customers came in and told us it hit a Ford F-150 just a kilometre outside of town. Just a fireball, he watched it hit."

Friends say the driver of the pickup truck struck by the minivan was an oil rig worker who was on his way to a work site.

"We lost a brother. A member of the team," said Blaine Abel, who spoke to CBC News at the crash site. "Yeah, we're just trying to piece anything together."

Abel remembered the man as someone with great character.

"Just an all-around good guy," he said.