A suicide car bomber rammed into an armored police vehicle in northwest Pakistan's main city on Wednesday morning, killing four officers and wounding 11 other people, police said.
The attack underscored the persistent threat of militancy to U.S.-allied Pakistan, despite army offensives in the tribal regions along the border designed to clear out Taliban and al-Qaida havens, AP reported.
The attack occurred at a checkpoint on the outskirts of Peshawar and also damaged some nearby houses, said Liaquat Ali Khan, a senior police official. Four civilians in the houses were among the wounded, he said.
The attacker used an estimated 440 pounds (200 kilograms) of explosives, police official Imtiaz Khan said.
Overall, Pakistan has seen relatively less violence since the start of this year than late last year, and most of the attacks have been on smaller targets, causing fewer casualties.
The decrease appears partly due to the army offensives in the tribal areas and other parts of the northwest.
On Tuesday, Pakistani troops killed eight alleged militants after a battle over a checkpoint in the Bezod area of Orakzai tribal region.
Airstrikes killed five more suspected insurgents in the Kasha area of Orakzai later Tuesday, local official Jahanzeb Khan said. Five suspects also were arrested in the Feroz Khel section of the tribal region, he said.
Two intelligence officials confirmed the account on condition of anonymity because they were not authorized to speak to media on the record.
The military escalated an offensive in Orakzai in mid-March after many Pakistani Taliban fighters fled there to avoid a separate offensive in South Waziristan tribal region.
The information is difficult to verify independently. Access to the region is restricted.