Bharatiya Janata Party observing 12-hour strike in West Bengal today

The strike will be observed by the main opposition party of the state from 6 am to 6 pm.

The protest march to West Bengal state secretariat Nabanna against the RG Kar rape-murder of a trainee doctor turned Kolkata into a battleground on Tuesday as police and mobs of students and demonstrators faced off at multiple locations en route to the administrative building in Howrah that houses the office of Chief Minister Mamata Banerjee.

The protest march turned violent in Satragachi in Howrah, in MG Road, Howrah Bridge approach and Bowbazar crossing in Kolkata as the mobs of protesters fought with the police who appealed for peaceful march while barricading all roads to Nabanna since last night.

Police said as many as 220 people were arrested in the students' protest march to Nabanna which turned violent forcing the cops to lathicharge and fire water cannons and teargas shells in Kolkata and its neighbouring city Howrah.

At least 15 policemen were reportedly injured in the clashes in Kolkata. The exact number of protesters injured in the agitation is unaccounted.

Earlier, tensions erupted at multiple locations in Kolkata and Howrah as protesters demanding resignation of Chief Minister Mamata Banerjee and justice for the Kolkata doctor, who was brutally raped and murdered inside RG Kar Medical College and Hospital, took to the streets to march towards Nabanna.

Police said the protesters hurled bricks, stones and bottles aiming at cops, and policemen restored to lathicharge, lobbed tear gas shells and used water cannons to disperse them.

Organizers of the protest, which was held by one unregistered organisation -- Paschimbanga Chhatra Samaj- alleged that police had "attacked" their "peaceful" rallies without any provocation and several of their protesters were injured.