KHAR, Pakistan -- A suicide bomber has killed at least 24 people and injured more than 50 others in an attack on a security checkpoint in northwest Pakistan.
Officials say the bomber struck on May 4 near a crowded market in Khar, regional capital of the Bajaur tribal district, on the border with Afghanistan.
The dead are reported to include two senior officers of the Bajaur Levies, a tribal police force in the remote region.
At least five other policemen were also killed.
Schoolchildren and other civilians were among the dead and injured.
A self-proclaimed spokesman of the Tehrik-e Taliban Pakistan has claimed responsibility for the attack.
Eyewitness Qadir Siyal described the attack, which hit during the morning rush hour when villagers crowd the market in Khar.
"I was coming from my village to the bazaar in Khar. Soon after we stepped out of the car, there was a huge blast near the main square in the bazaar," he told RFE/RL.
"The blast raised a cloud of dust and debris. The security forces soon cordoned off the area and began shooting into the air."
Bajaur, the northernmost among the seven tribal districts in Pakistan, has seen frequent fighting between the military and the Taliban and Al-Qaeda in recent years.
Two bomb blasts targeting anti-Taliban tribal elders and security forces killed five people in the Chamarkand area of Bajaur on May 3.
The Pakistani military conducted major operations in the region in 2008 and 2009, causing a large-scale displacement of civilians.
Despite the military's claims of clearing the region, Islamist militants there continue to launch attacks, most of them targeting anti-Taliban tribal leaders and militias.
With reporting by Reuters, dpa, and AFP