A bomb targeting a bus carrying government employees in the Pakistani city of Peshawar killed 15 people on Wednesday, officials said, with a militant group claiming it was a revenge attack for death sentences passed against Islamists.
The explosion took place on a main road after the bus picked up government workers from districts surrounding Peshawar to take them to work in the city.
Senior police official Mohammad Kashif said 15 people were killed and 35 wounded. A hospital official said the death toll was likely to rise.
"It's premature to comment about the nature of the blast but it appears that explosives were planted inside the bus," Kashif said. "There were 40 to 50 people on the bus."
Lashkar-e-Islam, a militant group allied with the Pakistani Taliban, claimed responsibility for the bombing, saying it was to avenge a military court's sentencing of 13 militants to death on Tuesday.
The men had been convicted of a range of offenses including the 2013 massacre of 10 foreign mountaineers. Pakistan executes more people per capita than any other country in the world apart from Iran and Saudi Arabia.
A video released by local newspaper Dawn taken during the aftermath of the bomb shows bodies of the dead and injured being carried out of what was left of the vehicle. Part of the roof of the bus has been blown off by the force of the explosion.
Pakistani security forces stepped up their fight against the Pakistani Taliban and allied militants along the border with Afghanistan after the massacre of 134 children at an army-run school in Peshawar in December 2014.
Bomb attacks have fallen off since then as the militants have been squeezed into smaller pockets of territory. However, militant groups remain able to launch sporadic attacks on security forces and civilian targets.
In January, more than 20 students and staff were killed when militants attacked Bacha Khan University in Charsadda, northwestern Pakistan.
Earlier this month, two Pakistani employees of the US consulate in Peshawar and some soldiers were killed by a bomb while on a drug-eradication mission.
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