Nearly 40 students were inside the dilapidated school building in Basti Ali Wala area of Multan when the roof collapsed, District Coordination Officer Zahid Aslam said.
A rescue operation was initiated immediately to pull out the children and teachers trapped under the debris. Nine students and two teachers who got serious injuries have been admitted to Multan's Nishtar Hospital.
After the incident, agitated parents of the students surrounded a police vehicle and protested against the school administration for their negligence regarding the dilapidated condition of the building.
Punjab Chief Minister Shahbaz Sharif has ordered officials to submit a report about the incident.