Armed assailants stormed into a building housing the office of a US based non-governmental organisation (NGO) on Wednesday killing at least five persons in Manshera region of North West Frontier Province (NWFP).

According to reports, extremists attacked the office of World Vision and killed five persons, including two women.

However, an aid worker put the death toll to six and said similar number of persons were injured in the attack.

"They opened fire and also exploded hand grenades. So far we have confirmation about the deaths of five people, including two women," The News quoted senior police officer Waqar Ahmed, as saying.

Another aid worker, while confirming the killings, said some of the staff member were feared trapped inside the NGO building.

"Five staff from World Vision are dead, six are seriously injured. More information is coming. The staff are trapped in the office," he said. (ANI)