A teenage suicide bomber killed 17 people at a busy Pakistani bus terminal on Wednesday, the third attack in three days as the country stepped up security for the holy month of Muharram.
The bomber blew himself up in Kohat, home to at least half a million people and one of the main garrisons for the Pakistan military, in the northwestern province of Khyber Pakhtunkhwa.
Around 4,000 people have died in suicide and bomb attacks across Pakistan since government forces raided an extremist mosque in Islamabad in 2007. The attacks have been blamed on networks linked to the Taliban and Al-Qaeda.
The northwest has been particularly hard hit. Pakistan in 2009 fought to wrest back control of the northwestern district of Swat from the Taliban and are fighting against homegrown insurgents along the Afghan border.
"It was a suicide blast. The death toll has risen to 17," Kohat police chief Dilawar Bangash said, adding that 25 others were wounded, seven of them seriously.
Police said that the bomber blew himself up at the door of a bus carrying passengers to the nearby tribal district of Orakzai, where Pakistan has encouraged displaced civilians to return after an anti-Taliban offensive.
"We have found the head and legs of the suicide bomber," said Bangash. The bus terminal is in Tirah bazaar, the main market in the town.
The attack coincided with the start of Muharram, which traditionally sees tensions rise between Pakistan's majority Sunni Muslim and minority Shiite Muslim community, and attacks on Shiite religious parades.
But police said that the target was not immediately clear.
"It is true there were more Shiites killed in the attack but there were a number of Sunnis also who died in the blast. So we cannot say who was the target," said Bangash, adding the suicide bomber was aged 15 to 16.
On Monday, a pair of suicide bombers killed 43 people, attacking anti-Taliban militiamen and pro-government elders in Mohmand, part of the tribal belt that Washington considers the global hub of Al-Qaeda.
The Pakistani Taliban purportedly claimed responsibility for that attack, threatening death to anyone who forms militias against the Islamists.
On Tuesday, a suicide bomber tried to assassinate the chief minister of Pakistan's southwestern province of Baluchistan, damaging his motorcade and wounding nine people but leaving the minister unhurt.
A purported spokesman for the banned extremist group Lashkar-e-Jhangvi claimed responsibility, saying the official had been targeted for efforts to provide security to Shiite Muslims, who are frequently attacked in Baluchistan