A powerful explosion ripped through a seminary in Pakistan’s Peshawar city on Tuesday, killing at least seven children and wounding 70 others, senior police officials said.

The blast occurred at the seminary in Dir Colony in interior Peshawar city after Fajr (morning) prayers. According to PTI, a bag filled with explosive materials was kept by some unknown person which went off, superintendent of police in Peshawar city Waqar Azeem said.

He said the bag is believed to have had an IED device that went off when the children started filling in the seminary.

The hospital authorities confirmed that they received seven dead bodies and 70 people injured in the blast.

There was a general threat alert in the Peshawar district, said Khyber Pakhtunkhwa police chief Sanaullah Abbasi, who also confirmed the death toll.

The seminary’s administration said around 1,100 students study at the institution.

Khyber Pakhtunkhwa Chief Minister Mehmud Khan condemned the attack on children.

Khyber Pakhtunkhwa Health Minister Taimur Saleem Jhagra visited the site of the blast. Speaking to reporters, he said that the focus was on providing the injured the best possible treatment to increase their chances of recovery.

Last month, five people were killed and two others injured in a blast in the Akbarpura area of Nowshera, Khyber Pakhtunkhwa.