STERLING HEIGHTS, Mich. (AP) — A fire chief says two workers have been killed after granite slabs shifted on top of them inside a Detroit-area business.

Sterling Heights Fire Chief Chris Martin tells WDIV-TV the incident occurred Monday afternoon at the business called the Stone Warehouse.

Martin says the slabs weigh about 1,000 pounds (454 kilograms) each and measure 5 feet (1.5 meters) wide and 8 feet (2.4 meters) long. He didn’t say how many slabs were on the men.

Firefighters evacuated the business while they worked to remove the slabs from on top of the men.

He says the circumstances that led to the slabs shifting are unclear.

The men’s names weren’t immediately released.