A father, his son and another person were injured when a crude bomb exploded in a vat in Phoolbagan on Thursday afternoon.

The blast took place when the trio, all rag-pickers, was rummaging through garbage vats. One of them started playing with the bomb, thinking it was a tennis ball.

The injured, Rashmohan Bala, 45, his 16-year-old son Rashu and Swapan Dey, 52, were admitted to RG Kar Medical College and Hospital, where their condition is said to be stable.

Gyanwant Singh, the deputy commissioner of police (headquarters), said: “The trio were rummaging through the vat in Surah Second Lane, in the Phoolbagan area, around 2.45pm. Rashu noticed the ball and playfully threw it against a wall.”

The bomb went off as soon as it hit the wall. All three suffered splinter injuries on their face, chest and abdomen.

“Pedestrians and other local people rushed to the spot and found the three lying by the road, groaning in pain. They were rushed to the hospital in a taxi,” said Singh.

All three had to undergo surgery to get the splinters removed. Officers of Phoolbagan police station suspect that local gangsters had hid the bomb in the vat.

“They often use garbage vats to hide crude bombs and other explosives. We are searching all other vats in the Phoolbagan area to recover more of these,” said an officer.

The police said such incidents are common. “In August, three children, aged between 10 and 12, were injured when they were rummaging through a vat in the Chitpur area. In most cases, they fail to identify a bomb and start playing with it, mistaking it for a ball,” said an officer of the detective department.