Kolkata, Oct 3 (IANS): A suo-motu case has been registered against unknown persons in Tuesday's bomb blast in West Bengal's Dumdum area, that killed an eight-year-old boy and injured nine others, a senior police officer said on Wednesday.

"In the Dumdum explosion, we registered a case against unknown persons on charges of murder, conspiracy and under various sections of the Arms Act. No one has been arrested or detained so far," Barrackpore Police Commissioner Rajesh Kumar Singh told IANS.

"We are checking the CCTV footages and speaking to the people in the neighbourhood. It's an ongoing probe," he said.

The officer said the remnants of the bomb and splinters recovered from the spot, have been sent for forensic tests to ascertain what type of explosives were used in the blast.

An explosion took place in front of a multi-storied building in the Dumdum's Nagerbazar area in North 24 Parganas district on Tuesday morning that ripped through adjacent shops, shattered window panes of nearby houses and damaged the pedestrian walk, besides killing a boy.

Police later revealed it was low-intensity socket bomb might have been used. Parts of the bomb ricocheted off the concrete floor and hit a terrace causing the impact of the blast to be double.

Bibhash Gosh who was injured in the blast, died at a state-run hospital later in the day while nine other including the deceased's mother remain hospitalised.

Trinamool Congress and Bharatiya Janata Party traded charges against each other for the blast.

While Trinamool claimed that the blast was masterminded by activists of the BJP-RSS to kill the chairman of south Dumdum municipality Panchu Roy, the BJP termed it to be a fallout of the ruling party's internal problems in the area.