The valley was once a TTP stronghold from 2007 to 2009.
Although peace has returned to the valley after a military operation in 2009, security had been a primary concern in the region. In 2012, Taliban militants had shot and severely injured Malala Yousafzai, who has campaigned for girls' education in Pakistan's northwestern tribal belt.
Government sources had said rescue teams reached the area and shifted the injured to a hospital in Saidu Sharif.
"God willing Tehreek-e-Taliban has started the process of revenge attack", the group's spokesperson Mohammad Khurasani said, according to Reuters.
This is the second attack in a month and it is suspected that TTP will carry out more of such attacks.
The military has been on alert for signs of a Taliban resurgence as it seeks to rebuild civilian institutions and win over the local population as a bulwark against radical ideology.
Prime Minister Shahid Khaqan Abbasi strongly condemned the attack, saying the coward terrorist enemy is no match for the valiant sons of the soil.
The prime minister said that no cowardly attack can deter Pakistan in pursuing struggle against the menace of terrorism to its logical conclusion.