Bolpur, Jan. 3 :    Bolpur, Jan. 3:  Twenty-one persons were injured when students of the Birbhum Institute of Engineering and Technology at Suri fought a pitched battle with the police today after an examinee was caught cheating during a first semester test. Trouble started when the invigilator snatched the answer-script of the student caught copying from a book. A group of angry students went to institute director Amitava Das Gupta and demanded an explanation as to why his paper was taken away. When the director said he was caught cheating, the students went on a rampage. The director called the police, making matters worse. Students started hurling stones at the police and a pitched battle ensued. In all, 17 students and four policemen were injured. A first-year student, however, said the examinee was expelled and the other students had gone to the director to protest against the decision. Das Gupta denied expelling the student. Examinations of different semesters have been postponed indefinitely, a spokesman of the institution said. Fifth-semester student Sagar Sudha Roy was seriously injured in the lathicharge. He was admitted to Suri hospital, where his condition is stated to be critical. Smritikona Pramanick, a student, alleged that the police entered the girls' hostel and beat up the inmates. But Manoj Verma, additional superintendent of police, denied the allegation.