Islamabad , Pakistan ( CNN ) -- A teenage suicide bomber killed at least 27 army recruits and wounded 42 others Thursday when he blew himself up at a military training center in northwest Pakistan , officials said . The Pakistani Taliban claimed responsibility for the blast , saying it was a `` message for those who wish to join ( the ) pro-American military . '' `` We will continue targeting Pakistan military until it stops supporting the U.S. , '' said Azam Tariq , the central spokesman for the group . The suicide bomber , who was about 14-years-old , was wearing a school uniform , a senior Pakistani military official said . The military official asked not to be named because he was not authorized to talk to the media . The teenager detonated his explosives after walking onto the grounds where army recruits were receiving their morning training , according to police chief Abdullah Khan . The bomber was either carrying the explosives in a bag or wearing a suicide vest , officials said . A school for children of military recruits is located inside the training facility . The attacker was probably pretending to be a student there , the military official said . The attack took place in Mardan , a district 50 kilometers ( 31 miles ) north of Peshawar in Pakistan 's Khyber-Pakhtunkhwa province , formerly known as the North West Frontier Province . Peshawar is the gateway to the country 's tribal region where security forces have been battling an insurgency led by the Pakistani Taliban . Journalist Nasir Habib contributed to this report .
NEW : The Pakistani Taliban claims responsibility for the blast . The suicide bomber was a teen wearing a school uniform . A school for the children of military recruits is located at the training facility . The bomber was either carrying the explosives in a bag or wearing a suicide vest .