A suicide bomber attacked the main border crossing for convoys ferrying supplies to U.S. and NATO troops in Afghanistan on Thursday, killing at least 19 security officers, officials said.
The assailant walked up to a group of border guards outside their barracks at the Torkham checkpoint in the Khyber region and detonated his explosives, police officer Sadiq Khan said. The border had closed for the day a few hours earlier.
Ali Raza, an official in the administration office, said he heard a huge explosion in the building next door.
"We rushed out and saw destruction all around," Raza said.
At least 19 people were killed and 20 wounded, according to Fazal Akbar, the head doctor at Landi Kota hospital, where the victims were taken.
The Torkham checkpoint marks the main crossing from Pakistan's Khyber Agency into Afghanistan.
U.S. and NATO troops in landlocked Afghanistan rely on the supply line for up to 75% of their fuel, food and other logistical goods. Thousands of civilian vehicles also use the route.
Pakistan's government dispatched paramilitary forces to escort supply convoys through the Khyber Pass after several attacks last year, and there has not been a major assault on a convoy for nearly six weeks.
No one claimed immediate responsibility for the bombing, but the Pakistani Taliban is a likely suspect.
Also in the border region, two U.S. missiles hit a suspected militant compound, killing six people, the latest in a string of such attacks, intelligence officials said.
Pakistan's lawless border with Afghanistan is a main front in the battle against Al Qaeda and the Taliban. Under heavy U.S. pressure, the Pakistani military has launched ground offensives and air attacks on the insurgents in recent months, but much of the region remains under militants' control.