Investigators are trying to figure out what caused a fire at Muskegon Castings Corporation late Tuesday, March 14.

The fire started in the ceiling around 10:30 p.m., but the flames burned well into Wednesday morning at the building, which is on Sheridan Drive.

Around 40 people were inside when the fire broke out. All of them made it out safely.

There are unconfirmed reports of an explosion. Workers say they didn't hear anything, but did see flames spreading across the ceiling.

This morning, folks are showing up for shifts not knowing what happened. Many are worried about their jobs.

The building is likely a total loss.

The fire spread so fast firefighters from several Muskegon area departments couldn't enter the building. They had to attack the flames from the outside.

"This is a catastrophic incident, it's a major fire," said Jeffrey Lewis, Muskegon's Director of Public Safety.

Because of a number of hot spots fire crews remained on scene for 12 hours.

Muskegon Castings makes automotive parts. The factory contained numerous flammable materials and propane lines.

"We are thinking there was an equipment malfunction," Lewis said.

Muskegon Castings runs multiple shifts. We are told there are around 100 employees.

Employee Julie Cooper arrived early Wednesday morning to work the first shift.

"It is just devastating," Cooper said. "It is sad it is gone."

Muskegon Castings is part of the Port City Group. That company runs other manufacturing businesses in Muskegon. Cooper says her supervisor is working to place her and other co-workers into those other factories.

"That is our family," Cooper said. "I'm just thankful nobody got hurt, a building can be replaced, a life can not."

The fire marshal says the building is a total loss. It's possible the company might be able to salvage some of the equipment and tools. Investigators are waiting for the building to cool before attempting to make the significant interior investigation needed to determine an exact cause.

Firefighters on the scene of an industrial fire at Muskegon Castings Corporation in Fruitport Township, Wednesday March 15.

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Matt Gard is the Senior Producer of the 13 Morning News. If you have a story idea, you can contact him on Twitter, @mgard_wzzm13 or by e-mail,