Two police vehicles were torched and four security personnel were beaten up by a mob after several houses were damaged following a loud explosion when a bomb disposal squad of CID was defusing firecrackers on the banks of Ganga in Naihati in North 24 Parganas district on Thursday.

Angry locals beat up three members of the Bomb Detection and Disposal Squad (BDDS) and a police constable besides torching two vehicles outside Naihati police station, triggering tension in the area. The residents also put up a road blockade, obstructing traffic.

Chief Minister Mamata Banerjee confirmed that a number of houses have developed cracks due to the intensity of the explosion and promised to help the dwellers, while Governor Jagdeep Dhankhar called for a thorough probe in view of the incident's 'seriousness, intensity and damage caused'.

"I have received reports that some houses developed cracks due to the intensity of the explosion that took place while bombs were being disposed off in water. I can assure you that if indeed some houses have developed cracks, we will definitely help them after reviewing the situation," said Banerjee.

"I am giving instructions to the District Magistrate in this regard. Don't be worried. If anybody suffers losses during our work, it is our responsibility to take care of that. We will do our duty," she said.

Banerjee also instructed local MLA Partha Bhowmick to go to the affected area.

The Governor said the explosion left nothing to imagination.

"It calls for a thorough probe in view of its seriousness, intensity and damage caused. Only expert investigation can unearth the issues involved. This ominous development should be eye opener for law enforcing and regulatory regime in the state," Dhankhar posted on his twitter handle.

Over the past few days, the police have been raiding illegal firecracker factories and seizing crackers and explosives following the death of four persons at a fireworks manufacturing unit in Naihati last week.

On Thursday, when the Criminal Investigation Department's (CID) bomb squad was deactivating the crackers at Ramghat on the banks of Ganga, there was a loud explosion leading to thick smoke filling the horizon over a large area.

"The entire area shook. The window panes of a number of houses were shattered. Some houses also developed cracks," said an eyewitness.

The locals, who had been asking the police not to deactivate the bombs so close to thickly populated areas, then went berserk and torched the vehicles of the security personnel.

"I would like to ask the police how can they carry out such explosions in an unplanned way when there are so many thickly populated areas around," said a youth.

The impact of the explosion was so severe that it broke a few window panes at Chuchura located on the other bank of the river in Hooghly district.

Barrackpore Police Commissioner Manoj Verma said a probe has been ordered to ascertain how the bombs were being disposed off.

"There was a huge quantity of explosives. But the BDDS team was there. They are the ones who decide how to dispose them off," he said.

The issue led to verbal fisticuffs between the ruling party and the opposition.

Demanding an NIA probe into the matter, state BJP President Dilip Ghosh said the explosion along with the sky-rocketing smoke reminded him of Hiroshima and Nagasaki, which were devastated by US atom bombs at the fag end of World War II in 1945.

"The scenes seen in Iraq and Kuwait (during the Gulf War in the 1990s) are now getting recreated in Bengal. Does the Chief Minister think she can manage everything by paying compensation," Ghosh asked.

"The sound of the explosion could be heard from a distance of up to 15-20 km. It seems the police personnel and BDDS team members had not seen such explosives in the past. There should be a probe to find out what chemicals were used and whether it was RDX," said Ghosh.

CPI-M politburo member Mohammad Selim said that under instructions from the Chief Minister, the police are making no distinction between firecrackers and bombs.

"The administration will find out who stored the explosives and why. The probe will find out whether there was negligence in defusing them. Ordinary crackers don't cause damage in houses in far off villages," said Trinamool Secretary General and state Education Minister Partha Chatterjee.