NEW DELHI -- At least three persons were killed in an explosion at a cracker factory in the central Indian state of Madhya Pradesh late Wednesday night, a senior police official said Thursday.

"The blast occurred at the cracker factory in the state's Balaghat district, triggering a massive fire in the area, in which some 12 houses were gutted," he said, on condition of anonymity.

While three factory employees were charred to death, some injured have been admitted to a local hospital, the official said.

A probe has been ordered into the incident, he added.

Fire often breaks out in cracker factories, mostly illegal, because of the poor safety standards.