It took firefighters more than 24 hours to stamp out the fire sparked by a tanker truck that rammed a Hells Angels bunker in Sorel-Tracy Saturday night. (Gilles Renaud/Canadian Press/Journal de Montréal)Quebec police say they're looking for two suspects and a blue pickup truck in connection with a weekend arson attack on a Hells Angels bunker in Sorel-Tracy.

Forensic experts combed through the bunker's charred remains Monday searching for clues in the attack, which destroyed the biker headquarters.

Investigators had to wait until Monday to start their work because the hollowed-out bunker smouldered for more than 24 hours after a tanker truck rammed into it.

The truck crashed into the garage-style building at high speed around 9:30 p.m. ET Saturday, according to authorities in the small town northeast of Montreal.

Eyewitnesses told authorities they saw a blue pickup truck shortly after the explosion, said provincial police spokesman Ronald McInnis.

"We think it is a getaway car," he said. "So, after the tanker truck goes into the bunker, they get away with that pickup."

The tanker truck used in the attack was stolen, but investigators haven't been able to determine whether it was carrying any explosive chemicals.

The fire was so intense that authorities ordered about 50 neighbours in the surrounding area to leave their homes.

No one was hurt in the fire, but the two-storey bunker is a writeoff.

The attack came nearly three days after three men with biker gang connections were arrested during raids in the Lower Saint-Lawrence area and in Montreal.

A Hells Angels bunker burned down in Sorel-Tracy. Police found nearly 1,200 kilograms of stolen explosives during the raids last Thursday.

The timing of both events has raised the possibility that a new round of biker wars has been ignited in the province, McInnis said earlier Monday.

"It's sure that we're going to consider whether the biker wars have started again. Perhaps there are other gangs that have issues with the Hells Angels," he told CBC's French-language service.

Quebec journalist and biker war expert Michel Auger believes the Sorel-Tracy attack could have been provoked by the Mafia, disillusioned bikers or former associates linked to the Hells Angels, he explained in an interview with Radio-Canada.

The bunker blaze was one of three fires reported in Sorel-Tracy on Saturday night.

Authorities said a fire was reported in a commercial building around 8 p.m., and a third blaze was discovered in a garage on Saint-Roch Road just before midnight.

The two other blazes are being treated as suspicious, but police said they aren't sure whether they are linked to biker gangs.