26-year-old scrap dealer Ram Nivas and his 20-year old helper Chotu were killed, while Ram Nivas's mother Mayadevi was injured in the incident.
"The accident occured when Ram Nivas was trying to extract brass out of the shell," Subash Chandra Dubey, SSP Agra said adding that, it was "purely an accident."
Mayadevi has been shifted to a nearby hospital for medical treatment, he said.
"However, samples of the mortar pieces have been collected for investigation and the local army authorities informed," Dubey said.