Peshawar hospitals have been inundated with wounded people
At least 30 people have been killed in a suicide car bomb attack in Pakistan, officials say.
The attack - at a paramilitary checkpoint 20km from the north-western city of Peshawar - comes as elections for president are under way.
About 70 people were also wounded by the blast, most of them civilians, reports said.
The attack comes after three days of continuous raids and airstrikes by US-led forces in Pakistan's tribal areas.
Five police officers were among those killed, said Peshawar police chief Muhammad Suleman.
A BBC correspondent says the attack happened close to a market by the checkpoint.
The powerful explosion destroyed part of the market, trapping many people under the debris, officials say.
Witnesses told the BBC the attack had been carried out by a suicide bomber in a pick-up truck.
"I saw the vehicle park itself next to the market, and then it blew up", a roadside hotel owner told the BBC.
There was no immediate claim of responsibility for the bombing.
Television pictures showed wrecked vehicles and widespread destruction in the marketplace. The blast left a crater one-metre (3ft) deep.
At Lady Reading Hospital in Peshawar, medic Mohammad Idrees said they were treating people for multiple injuries.
"We have declared an emergency here," he said.
From his hospital bed, 15-year-old Sher Zaman told the AP news agency that he had been selling fruit from a cart at the market when he heard a large explosion and something hit him in the chest, knocking him flat.
He said residents quickly gathered and helped to ferry casualties to hospital.