Police in India fired teargas and water cannon to disperse hundreds of protesters marching in the eastern city of Kolkata on Tuesday to demand the resignation of a top state minister in the wake of a gruesome rape and murder of a trainee doctor.

Protesters led by university students broke through the iron barricades set up on the route of their march to the West Bengal state secretariat, television footage showed, resulting in a baton charge by the police, who had earlier declared the protest illegal.

The August 9 attack on the 31-year-old doctor has caused nationwide outrage, similar to the widespread protests witnessed after a 2012 gang-rape of a 23-year-old student on a moving bus in New Delhi, with campaigners saying women continue to suffer from high levels of sexual violence despite tougher laws.

A police volunteer has been arrested for the crime and the federal police have taken over the investigation.

Junior doctors have refused to see non-emergency patients in many parts of the country since the incident at Kolkata’s state-run R.G. Kar Medical College, as they launched protests demanding justice for the victim and greater safety for women at hospitals.

India’s Supreme Court has created a hospital safety task force and has requested protesting doctors return to work, but some have refused to budge, including in West Bengal, of which Kolkata is the capital.

On Tuesday, more than 5,000 policemen were deployed in Kolkata and the neighbouring city of Howrah, a senior officer said, as the protests led by some university students took off, demanding the resignation of West Bengal Chief Minister Mamata Banerjee.

Kunal Ghosh, a spokesperson for Banerjee’s ruling Trinamool Congress Party, blamed the police crackdown on “lawlessness” created by workers of Prime Minister Narendra Modi’s Bharatiya Janata Party, which is the main opposition party in the state, as well as groups affiliated to it.

The BJP has extended its support to the protesting students, while senior state leader Suvendu Adhikari told reporters that Banerjee’s administration was trying to suppress the rape and murder incident — a charge the state government has denied.