The murder of a radical student leader in India's eastern state of Bihar has provoked countrywide protests leading to confrontations between police and protesters.
Chandrashekkar Prasad was a former president of the students' union at New Delhi's Jawaharlal Nehru University, where he was active in the Communist Party of India (Marxist-Leninist), an ultra-left group which is leading a movement against the "land mafia" in Bihar, one of India's most backward regions.
Mr Prasad headed a campaign in Siwan district to "liberate" land alleged to have been taken from poor peasants by a local mafia close to the ruling Janata Dal.
Mr Prasad's party and other left student groups say his murder was political and demand the resignation of the state chief minister Laloo Prasad Yadav.
During a visit to New Delhi the minister was trapped inside his guest house by angry students. Police fired into the air to rescue him.
The night-long confrontation was reminiscent of student radicalism in the 1960s when vice chancellors and others were routinely gheraoed - a term coined by the Indian media to describe the act of surrounding and detaining someone.
Jawaharlal Nehru University, the scene of many past protests, has become the hub of agitation with a committee coordinating demonstrations in other campuses.
Student activists are touring universities outside New Delhi and a march on parliament is planned.
Human rights organisations have demanded that the Central Bureau of Investigations set a deadline for publishing its findings.