The police burst 35 rounds of tear gas shells to disperse a group of students of a central Calcutta college, who had turned violent and attacked the police with brickbats and crackers this afternoon [December 19, Calcutta]. To-day is the second day of the United Front-sponsored civil disobedience movement in West Bengal. According to the police, 18 persons were arrested in this connection. Of the 11 police personnel injured, two were admitted to hospital. Police said that shortly after midday, over 50 students held a meeting at the college gate and started interfering with the running of trams and buses. In the melee, a tramcar was set on fire and it was gutted, as fire brigade personnel could not reach the spot in the barrage of brickbats. When the police reached the place, they were greeted with heavy brickbats from the rooftop of the college. Subsequently teargas was used to disperse the crowd. Vehicular traffic remained suspended in the area for a long time. According to a Home Department spokesman the police have been advised that they may enter the premises of educational institutions if it was found necessary to deal with situations such as this. Earlier, two rival groups of students were involved in a violent clash in the Presidency College over the question as to whether or not the students should respond to the call for civil disobedience movement to-morrow. Brickbats were freely used and some crackers were also hurled. Vehicular traffic was withdrawn from the area as a precautionary measure. Police said brickbats were thrown against them when they intercepted the students of a north Calcutta college who were taking out a procession. In another case, 14 arrests were made when a group of students went in a procession with banners, shouting slogans in north Calcutta. They fled as soon as the police arrived.