Pakistani officials are investigating an explosion at a border crossing with Afghanistan that set ablaze at least 16 supply trucks and fuel tankers bound for NATO troops.
Police suspect a bomb planted under a fuel tanker exploded late Sunday at the Chaman crossing in Baluchistan province. The blaze then spread to the other trucks.
Sources say at least one person was wounded in the incident.
Witnesses report hearing gunfire before the explosion, and police say emergency crews were fighting the fire into Sunday night.
Hundreds of trucks, many loaded with NATO supplies, have been stuck on Pakistan's side of the border. The Chaman crossing had been closed for two days because of a dispute between Pakistani and Afghan customs officials relating to the inspection of goods.
Pakistani police say they foiled an attack on supply trucks earlier Sunday when they found and defused a bomb.
The Chaman crossing is one of two main crossing points for supplies destined for American and NATO troops in Afghanistan.
Earlier Sunday, at least 16 police recruits were killed by a suicide bomber in the Swat Valley, the deadliest attack since the military said it took control of the area from Taliban militants.
And the army said it killed at least 14 militants Sunday in operations near the town of Charbagh in Swat.
Pakistan's government launched an offensive in late April aimed at clearing militants from the greater Swat valley region.
Some information for this report was provided by AP and Reuters.