Two employees of a granite and marble business in suburban Detroit were fatally crushed Monday afternoon when multiple slabs of granite fell on them.

Sterling Heights Fire Chief Chris Martin said it appeared that the workers were using an overhead crane to move the slabs – each weighing more than 1,000 pounds. When slabs were lifted off their storage rack, others shifted, causing slabs to fall on the men.

The incident at Stone Warehouse of Michigan occurred inside a warehouse shortly before 3 p.m. The building was initially evacuated so that officials could ensure the safety of other employees while the slabs were moved. Police and fire personnel got an assist from workers from nearby granite companies, who went to the Stone Warehouse facility to help move the fallen slabs.

According to news reports, recovery efforts lasted into the night, with one body being recovered at approximately six p.m., and the other three hours later.

One of the victims was in his 30s, the other in his 50s.

Michigan OSHA was notified about the incident.