At the Sayed ul Shuhada high school, girls and boys study in three shifts, the second of which is for female students, Najiba Arian, spokeswoman for the Ministry of Education, told Reuters. The wounded were mostly female students, she said.
A spokesman for the interior ministry, Tariq Arian, said the death toll was at least 30 with 52 injured.
At a nearby hospital, staff wheeled in injured students while dozens of distressed relatives searched for their sons and daughters, according to a Reuters witness.