A suicide bomber has blown himself up near a sports stadium in Pakistan's volatile northwest, killing at least four people and wounding more than 13 others.
Authorities say the attack took place Tuesday at Qayyum Stadium in Peshawar, the capital of North-West Frontier Province, shortly after the closing ceremony of the inter-provincial games.
No group has claimed responsibility for the blast, which President Asif Ali Zardari and Prime Minister Yousuf Raza Gilani strongly condemned.
Authorities say provincial officials who attended the closing ceremony may have been the intended targets.
Also Tuesday, Pakistani security forces backed by helicopter gunships were searching for 13 supply trucks and their drivers, hijacked by gunmen in the Khyber tribal district.
The convoy was carrying supplies for Western forces in neighboring Afghanistan when it was ambushed late Monday.
A district administrator said the trucks were seized in four places along a 35-kilometer stretch of road by around 60 masked gunmen. He blamed the hijacking on militants loyal to Taliban commander Baitullah Mehsud.
The Khyber Pass is a major supply route for U.S. and NATO forces in Afghanistan.
Elsewhere in the northwest Tuesday, Pakistan's army says seven militants have been killed in clashes with troops in Swat Valley.
The army says the fighting took place during a military operation in Matta and Kabal districts. Several militants were wounded in the exchange of gunfire.
Some information for this report was provided by AFP, AP and Reuters.