A large building caught fire in Michigan City Saturday, sending toxic clouds of smoke into the air.

The property manager of the building believes the fire was arson.

Investigators with the fire marshal’s office are still looking into the exact cause of the fire.

Mikropor America, Incorporated uses the building to make HVAC products.

Ed Bohle who manages the building says he’s had issues recently with people breaking into the building after hours, and thinks it was people who broke in again who started the fire.

He says it caused over 250-thousand in damages.