The labourers were engaged in quarrying of stones when a heap fell on them trapping six under debris, Senior Superintendent of Police Vinay Kumar said.
While two labourers - Ajay Paswan and Surendra Paswan - were killed on the spot, four others received injuries, he said.
The injured were admitted to the Anugrah Narayan Magadh Medical College and Hospital, the SSP said.
The quarrying licence of the contractor was being verified.
