MUSKEGON, Mich. (WOOD) — The call on Monday came in as a kitchen fire — routine for firefighters in most circumstances. But this fire was anything but routine.

Arriving Muskegon Township firefighters found they had much more on their hands.

“This is what we pulled up on, with heavy black smoke coming out of the front of the home,” Muskegon Township Fire Inspector Mark Nocolai said, showing a picture of the home on Laketon Avenue with a picture window blown out in the front yard.

It was no stovetop grease fire. Something inside the kitchen caused an explosion, knocking drywall off twisted wall studs.

One of the people who escaped confirmed what Nicolai knew would eventually become a problem for firefighters.

“It was determined at that point that they were doing some process of manufacturing hash oil,” Nicolai said.

It’s an emerging problem he learned of during a recent training conference.

“In Michigan, it’s relatively new,” he said. “It’s predominant out in the western states. The instructor I had came from one of the western states, and he advised us that if we haven’t seen this yet, more than likely it is coming. “

The oil, when extracted from the marijuana plant, contains a high amount THC, pot’s psychoactive ingredient. But getting it out of the plant is tricky and hazardous.

“It’s very, very dangerous and very explosive,” Nicolai said.

Methods vary, but generally, butane or propane is used to saturate the plant and extract the oil. But the gasses have to come back out of the final product. That’s done by either cooking it on a stovetop or freezing it out in a refrigerator.

Butane and propane are highly flammable. The smallest spark — anything from static electricity to a refrigerator compressor — can set off that gas.

The process isn’t only dangerous for the people cooking it. Firefighters are put at a higher risk.

“There’s always the hazard of secondary explosion,” Nicolai explained. “Are there residual containers around that haven’t exploded?”

On top of being dangerous, it’s illegal in Michigan to process marijuana with butane.

The case has been turned over to police.