At least 11 persons, mostly students, were killed as burqa-clad militants stormed the hostel of the Peshawar Agricultural Training Institute in Pakistan on Friday, officials said.

The number of casualties is expected to rise, the media quoted security officials and doctors as saying. Thirty-seven others were injured in the macabre assault. 

The attack, claimed by the Tehreek-e-Taliban Pakistan, began early in the morning after three loud explosions were heard. Firing broke out at the hostel after three or four burqa-clad suspects entered the building, Geo news reported.

The Army's Inter-Services Public Relations confirmed the casualties. It said three terrorists were killed by security forces.

Suicide jackets, three grenades, two bombs and a pistol were recovered in the hostel building.

Khyber-Pakhtunkhwa Chief Minister Pervaiz Khattak said that although the police were "always alert, this incident happened suddenly", Dawn news reported.

"The police arrived and took control... Security measures have been taken keeping Eid Milad-un-Nabi in view. Our police was there soon after the firing started... Right now we are facing difficult circumstances."

There were fewer students at the hostel on account of Eid Milad-un-Nabi, the birthday of Prophet Mohammad.

Ordinarily, there are around 400 students at the hostel but there were only some 150 on Friday, said a student who witnessed the attack.

As two militants began firing, the frightened students ran to take shelter. Some were shot and wounded while others jumped out of the windows, the witness said.

The attackers, who arrived in a rickshaw, first shot the guard at the gate and then proceeded to the hostel, according to police.

Peshawar has for decades witnessed militancy at close quarters as it is seen as a frontline in the war against terrorism as well as due to its proximity to the restless tribal areas and the Pakistan-Afghan border.