At least 13 people have been killed and 10 wounded in a bomb attack on a Pakistani air force bus near the north-western city of Peshawar, police say.
The attack near Badaber, an air force base on the outskirts of the city, completely destroyed the bus.
The bomb went off as the bus drove over a bridge. Civilians were reported to be among the passengers.
It is the first such attack in weeks and comes as Pakistani troops battle militants in parts of the north-west.
The police chief of North West Frontier Province, Malik Naveed Khan, said the bomb appeared to have been remotely detonated.
Reports said the explosion left a huge crater. The bus was reduced to a tangle of twisted metal and debris.
Civilians die in Pakistan battles
An eyewitness said the explosion tossed the vehicle into air, and it caught fire.
"I saw the men on fire inside the vehicle, they were crying for help," he said.
"People rushed to the vehicle and started pulling out the dead and injured. The police arrived at the scene after an hour."
The injured have been taken to Lady Reading hospital in Peshawar.
The BBC's M Ilyas Khan in Karachi says this is the first direct attack on security forces in several weeks.
The bombing comes soon after Taleban fighters threatened they would retaliate against government forces for military operations against fighters in the Bajaur tribal region near the Afghan border.
Tuesday's attack may be a response to the security operation in Bajaur, our correspondent says.
PHOTO CAPTION
Map of Peshawar, Pakistan
BBC