The incident occurred at a factory here that manufactures items for the Indian Army, Senior Superintendent of Police (SSP) Shalabh Mathur said.
The boiler burst at about 12:30 P.M. Leaving the seven labourers injured who were working there, he said.
One of the victims, identified as Subhash Yadav, 40, was admitted to a private hospital where his condition was said to be stable, Mathur said adding the other six were sent to the government-run Hallet hospital.
Police are investigating the matter and factory owner is being interrogated, the SSP said.