Kolkata: Twelve students, appearing for their Madhyamik geography paper on Saturday, were barred after being caught with mobiles. The cases were reported in Kolkata, N 24 Parganas, Hooghly, E Midnapore, Bankura, Cooch Behar, Birbhum, W Burdwan. Khanna School, Kolkata, students were accused of vandalising their centre, Momin School. tnn