At least 73 people were killed in twin bombings to hit a paramilitary force academy in north-west Pakistan Friday in what appears to be a retaliation to avenge the death of al Qaeda leader Osama bin Laden by U.S. security forces in Pakistan earlier this month.

Authorities say the number of dead could rise as they search the rubbles at the training center for the Frontier Constabulary in Shabqadar, Charsadda district. Police says both attacks were caused by suicide bombers.

Earlier, Taliban in Pakistan warned to avenge the death of bin Laden by U.S. commando in a daring raid in his hideout in Abbottabad in northern Pakistan on May 2.

Witnesses claim the suicide bombers attacked while newly trained newly trained cadets from the Frontier Constabulary were getting into buses to enjoy a short leave giventhem after completing their training course.

Ahmad Ali, a wounded paramilitary policeman, told AFP news agency, "I was sitting in a van waiting for my colleagues. We were in plain clothes and we were happy we were going to see our families."

"I heard someone shouting 'Allahu Akbar' [God is great] and then I heard a huge blast. I was hit by something in my back shoulder. In the meantime I heard another blast and I jumped out of the van. I felt that I was injured and bleeding."

Officials said 65 of those killed were cadets, but there were also civilians amongst the casualties. Those injured were rushed to a local hospital while Pakistani security forces cordoned off the area.

Footages showed a number of vehicles destroyed or damaged because of the powerful blasts.

Shabqadar lies on the border with Afghanistan, about 35km (22 miles) north-west of Peshawar, which is near the Taliban stronghold of Mohmand.

The Pakistani army is expected to issue a statement condemning the attacks and highlight it as an illustration of their sacrifices in the "war on terror." The Pakistani military is under intense criticism and scrutiny over bin Laden and how the terrorist managed to live in Pakistan for six years near one of its military centers without its knowledge.