Calcutta, July 19 :     High drama was enacted on Central Avenue on Wednesday, with a bus being hijacked in broad daylight by students desperate to prove a point or two to the police. Chhatra Parishad supporters hijacked a bus hired by the city police at gunpoint, even as the vehicle was taking them to Presidency Jail from the scene of an agitation. The bus was filled with Chhatra Parishad activists arrested from Phears Lane for violating the law to protest abolition of the Higher Secondary courses from several colleges. Police personnel escorting the agitators were threatened and dragged out of the bus and the driver was forced to get off on C.R. Avenue. One of the students drove the bus to Calcutta Medical College and Hospital and as the vehicle was negotiating a U-turn, it almost hit a couple of pedestrians, according to the police. Senior officials were informed of the hijacking after the policemen chucked out of the bus called up the nearest police station. The student activists turned violent once they reached the hospital. They ransacked the enquiry office and its adjoining offices. Doctors on emergency duty fled the scene and patients and their relatives were seen scurrying for shelter. 'They took the bus to the hospital as some of them were injured in the clash with the police when they violated the law. They were trying to ensure proper medical attention for their injured colleagues. Chhatra Parishad president Subhankar Sarkar was also injured in the clash,' said DC headquarters Nazrul Islam. Police officials had to resort to a lathicharge to control the situation at the hospital. Some student activists were also arrested in connection with the violence. Sarkar was admitted to the hospital for treatment, the police said. Trouble began around 2 pm as a large number of Chhatra Parishad supporters converged on Phears Lane from College Street and Hazra for their law-violation programme. 'Suddenly, a group of agitators turned violent,' police said. The area soon turned into a battlefield, with stones being hurled at the police from all corners. Passing vehicles, too, were stoned. Pedestrians and policemen received injuries and five buses were badly damaged in the attack. Chaos reigned as pedestrians ran around, seeking shelter, while the street fight raged. Shopkeepers were quick to down shutters, fearing further trouble. Realising that the situation was spinning out of control, the police resorted to a lathicharge and chased the student demonstrators away from the spot. While Chhatra Parishad members later alleged that the police had lobbed teargas shells at them, police officials insisted that only a mild lathicharge had been launched to disperse the unruly mob. The clash resulted in traffic snarls on C.R. Avenue and its adjoining areas for more than two hours in the afternoon. Nazrul Islam said that 27 persons, including a woman, were arrested in this connection. Seven policemen were injured in the clash. 'We have identified the youth who hijacked the bus hired by us for the law-violation programme. He has been arrested,' said Islam.