"The incident took place this morning when Mangal Rathod was showing his unlicensed weapon", Mumbai Police spokesman Ashok Dudhe said.
"Mangal misfired and it hurt his chest. He was admitted to the nearby Sion civic hospital where he died," Dudhe added.
He said on the basis of a witness, police are investigating the matter.
Meanwhile, an official at the Wadala Truck Terminus police station said, "We have registered a case of accidental death, but investigation is going on with other angels like possession of the weapon and his link-ups with the other people.