Chandigarh, July 31 - Three former students of a government school here who were under suspension entered the school and one of them slapped a teacher while she was taking a class, police said.

According to police, a case was registered against the three teenaged boys Friday after a formal complaint was received from the principal of Government Model Senior Secondary School, Sector 35, Thursday.

'We have registered a case and started our investigation. We are raiding their possible hideouts and very soon we will arrest the culprits,' said Anokh Singh, investigating officer of the case.

On Monday an economics teacher was teaching students of Class 11, when three former students, who were suspended from the school, entered the classroom and started disturbing the students.

When the teacher tried to intervene, one of them slapped her and they fled after threatening her.