Islamabad, Pakistan (CNN) -- A young, female suicide bomber was behind a blast in Pakistan that killed at least 46 people and injured 105 others at a food distribution point, an official said Sunday.
Zakir Hussain Afridi, the top government official in Bajaur Agency, Pakistan, said that the preliminary investigation into the explosion shows that a girl between the ages of 16 and 18 blew herself up. The determination was made from remains of the bomber that were recovered.
The Pakistani Taliban claimed responsibility for Saturday's blast in that Asian nation's tribal region.
Azam Tariq, the central spokesman for the Pakistani Taliban, told CNN in a phone call that it targeted people who had formed what he called a pro-government and anti-Taliban group.
The blast took place about 600 meters from a U.N. World Food Programme distribution point at a security checkpoint in Khar, according to Amjad Jamal, a spokesman for the agency. He said that more than 300 people were going through a security screening to get food and other items at the time of the explosion.
Khar is the headquarters of Bajaur Agency, one of the seven districts of Pakistan's tribal region bordering Afghanistan. Jamal said that those who had been internally displaced during military efforts in Bajaur Agency get a month's supply of food and other goods.
Afridi said that the suicide bomber was in a burqa, a traditional full-body covering worn by some Muslim women. He said she was stopped for a security check at a checkpoint, where she detonated herself.
The official said it was the first instance of a female suicide bomber in Pakistan that he could recall, though various international news groups have reported at least one previous case of a female suicide bomber in the country. The New York Times reported a woman detonated explosives in Peshawar in 2007, killing herself.
The Pakistani Taliban denied that the bomber was a woman.
"We have thousands of male suicide bombers ready who are keenly waiting for their turns. Then why would we use a woman, which is against the traditions of Islam?" the Pakistani Taliban's Azam Tariq said.
Jamal said all staff members of the World Food Programme and its partner organizations are safe, but added that all four of the program's food distribution points in Bajaur Agency have been temporarily closed for security reasons. Still, the U.N. agency will continue to provide services elsewhere in the country, Jamal said.
U.S. President Barack Obama issued a statement condemning Saturday's "outrageous terrorist attack," which he called "an affront to the people of Pakistan and to all humanity."
"The United States stands with the people of Pakistan in this difficult time, and will strongly support Pakistan's efforts to ensure greater peace, security and justice for its people," Obama said.
The blast took place a day after about 150 militants fired at five security checkpoints in Mohmand Agency -- another of the seven districts in Pakistan's volatile tribal region along the Afghan border -- killing 11 soldiers. Security forces later killed 40 militants who were among the group, authorities said Saturday.
The security forces pounded militant hideouts in Mohmand Agency with helicopter gunships, said Maqsood Amin, a senior government official in the area. Twenty-four militants were killed during retaliation Friday while 16 were targeted Saturday.
CNN's Chris Lawrence contributed to this report.