The roof collapsed while masonry work was going on in the factory, killing Ramesh Maheshi, a labourer and the owner's son Sahil Sardana (23), on the spot, Deputy Superintendent of Police Shamsher Singh Dahiya said.
Fire tenders and locals rescued the other labourers trapped in the debris, he said, adding injured have been admitted to local hospitals and were stated to be out of danger.
However one injured person has been transferred to Agroha Medical college in a critical condition, the DSP said.