Violence broke out between two groups when a Ram Navami procession was taken out in West Bengal's Howrah city, where several vehicles were torched and shops were ransacked on Thursday evening.

Police said a number of people were detained in this connection.

Chief Minister Mamata Banerjee, who is on a dharna, said strict action will be taken against the culprits.

A police officer said the incident occurred when the procession was passing through the Kazipara locality.

Several shops and auto-rickshaws were ransacked during the violence while a number of cars including a few police vehicles were set on fire. Four fire tenders were pressed into service to extinguish the blaze.

The police used force to disperse the mob. A large contingent of police was deployed in the locality where the situation is stated to be under control.

The chief minister slammed the BJP for allegedly trying to stoke communal tension during the Ram Navami procession in Howrah and said those involved in the incident will not be spared.

"I have repeatedly said that I will not block any Ram Navami procession. I had given clear instructions to the police in this regard. While one community is celebrating Annapurna Puja, the other is observing fast during Ramzan," she said while concluding her 30-hour extended sit-in in a demonstration in the city.

"Those who were involved in today's violence will not be spared. I do not support riot mongers and consider them the enemy of the country. The BJP has always targeted Howrah. The other targets for them are Park Circus and Islampur. Everybody must be alert in their localities," she said.

Senior BJP leader Suvendu Adhikari, however, dubbed the allegations as baseless.

"The chief minister and the state administration are responsible for the violence," Adhikari, the Leader of the Opposition in the West Bengal assembly, said.