Dimapur, June 27 (IANS): Two people were killed and two others injured in a grenade blast at a warehouse in a hospital campus in Nagaland's commercial hub Dimapur on Saturday evening, police said.

All the dead and the injured belong to one family, police said.

The deceased were identified as 40-year-old Prakash Vishwakarma and his daughter Ruth Gurung, while the two injured were Prakash's son-in-law Deepak Gurung and grandson Robin, who is only four years old.

Police said Prakash, who worked at the hospital, was using a part of the warehouse as his residence.

"Prakash came home around 1.30 p.m. and was seen handling a grenade like object. The blast took place around 5 p.m. and it instantly killed him and his daughter Ruth," a police official said quoting witnesses.

Deepak, who was whitewashing the room at that time, received critical injuries along with his son Robin, who was playing in the room.

Prakash's wife was out during the blast and thus survived, police said.

"Preliminary investigation revealed it was a grenade explosion. We are not sure as to how the grenade came to the house. We are looking into the source of the grenade," the official added.