The incident happened just before 8 a.m. at a Stone Crest Way quarry in Sterling, the Worcester County District Attorney's Office said. The man's name was not released.
The man's body remained trapped beneath the rubble Thursday afternoon. State, local, and federal responders were working to retrieve it.
Firefighters determined there were no signs of life using video equipment.
Sterling authorities ordered that workers stop all earth removal operations until the Occupational Safety and Health Administration could investigate the incident, the prosecutor's office said.
Onyx Corporation, which runs the quarry, also halted work at sites in Acton, Leominster, and Westford until Monday.
Officials with the US Department of Labor Mine Safety and Health Administration were on the scene Thursday to oversee the safety of the retrieval efforts.
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