The incident occurred around 2 pm when the RPF constable was receiving the INSAS rifle from a colleague during change of duty.
"Splinters from the bullet hit a woman, her nine-year old son and a Metro employee," she said.
The woman and her son were waiting to buy tickets for their travel in the Metro at the crowded Dum Dum Metro station, which is located just below the Dum Dum junction station of Eastern Railway's Sealdah main section.
The passengers, Sangeeta Basu, her son, and Metro employee Niranjan Majumdar were rushed to nearby R G Kar Medical College and Hospital, Banerjee said, adding Metro Railway's Chief Medical Superintendent Mihir Chowdhury and Principal Chief Operations Manager Satyaki Nath rushed there to provide logistical assistance.
The child was injured in one leg, his mother suffered splinter injury in one hand and the Metro staff was hit in his body. The injured were given first aid at the hospital and released as their injuries were not serious, she said.
"The general manager of Kolkata Metro Ajay Vijayvargiya has ordered a high level inquiry into the incident and has assured of stern action against those found guilty," Banerjee said.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)