A suicide car bomb attack hit a Pakistani police checkpoint on the outskirts of Peshawar before dawn on Wednesday, killing four police and wounding 10 people, including a woman, police said.
The attacker struck close to the control post in Tir Bala village, on the main road from Pakistan's northwestern capital to Mohmand, one of seven districts in the Al-Qaeda and Taliban-infested tribal belt on the Afghan border.
"The vehicle was coming from the tribal area. It was full of explosives and the suicide attacker was coming from Mohmand," police official Liaqat Ali said.
"Four policemen were killed," he told AFP by telephone.
The force of the explosion destroyed the simple, one-storey mud-brick building at the police post, damaged a nearby house and a mosque, police said.
Those who were killed had been on duty at the checkpoint at the time of the attack, between 4:30 and 5 am, said police official Mussarat Khan.
"The small building at the police checkpoint was destroyed. A nearby house and a mosque were also damaged," he said.
Northwest Pakistan suffers from chronic insecurity, largely connected to the semi-autonomous tribal belt near Afghanistan, which Washington calls the most dangerous place on earth and a global headquarters of Al-Qaeda.
Tir Bala straddles Warsak Road, which links Peshawar, a city of 2.5 million, to the mountains of the tribal badlands, which became strongholds for hundreds of extremists who fled Afghanistan after the US-led invasion in late 2001.
Mohammad Gul, a police official on duty at Peshawar's Lady Reading Hospital, confirmed the death toll and said 10 people were wounded in the blast, including seven policemen, a cleric, a woman and a civilian man.
A campaign of suicide and bomb attacks has killed nearly 3,300 people in less than three years across the nuclear-armed country of 167 million. The attacks are blamed on Al-Qaeda, Taliban and other extremist Islamist groups.
Under US pressure, Pakistan as of last year significantly increased air and ground offensives against homegrown militants in the tribal belt, which Washington has called a global headquarters of Al-Qaeda.
But the rugged region is also routinely hit by US drone attacks targeting Al-Qaeda-linked and Taliban commanders, particularly the district of North Waziristan. The most recent attack on Monday killed eight Islamist militants.
More than 880 people have been killed in nearly 100 drone strikes in Pakistan since August 2008. The bombing raids fuel anti-American sentiment in Muslim Pakistan and draw public condemnation from the government.