At least seven people have died and at least 80 others injured after an explosion during a class at a religious school in northwest Pakistan.
Police initially said that children were among the dead, but later confirmed that almost all the students were in their mid-20s.
Hospital officials said all those killed were adults, while several children were among the wounded.
No group has yet claimed responsibility for the attack, which happened at around 8.30am local time, and an investigation has been launched.
Police officer Waqar Azim said that it appeared the bomb went off minutes after someone left a bag at the Jamia Zubairia madrassa, in the Pakistani city of Peshawar, situated near the border with Afghanistan, at around 8.30am local
Peshawar police chief Mohammad Ali Gandapur said the bomb contained up to 6kg (13lb) of explosives.
Student Mohammad Saqib, 24, said religious scholar Rahimullah Haqqani was explaining verses from the Koran when they heard a deafening sound followed by cries and saw blood-stained students crying for help.
“Someone helped me and put me in an ambulance and I was brought to hospital,” he said.
Authorities fear the number of dead from Tuesday’s attack could rise as several of the wounded are in a critical condition.
Saeed Ullah, 24, who witnessed the blast, said there was up to 500 students present at the time.
It comes days after an explosion just over the border in Kabul, Afghanistan, killed at least 24 people at an education centre – including students.
In 2014, Taliban gunmen killed more than 130 children in a school attack in Peshawar.