Suspected militants have killed more than 300 civilians and security personnel in the last month in an attempt to weaken the country's resolve to continue the military operation in the tribal area of South Waziristan, where al Qaeda and Taliban leaders are believed to be hiding.
Police opened fire on the pickup truck as it approached a checkpoint in front of a police station in Badh Ber, but the driver was able to detonate his explosives, said Liaqat Ali Khan, the senior police chief in the main northwestern city of Peshawar.
The attack, which partly damaged the station and destroyed a small mosque and a house nearby, killed three people and injured 20 others, said Khan.
Local television footage showed rescue workers searching for survivors and police examining the deep crater caused by the explosion.
A senior government official in the area, Sahibzada Anees, said the death toll may rise as rescue workers continue their search through the debris.
"This is an obvious reaction to the operation in the tribal areas," Anees said.
Badh Ber is located some 7 miles (12 kilometers) south of Peshawar. The area in and around the city, which borders Pakistan's semiautonomous tribal region, has experienced a wave of attacks since the army launched its South Waziristan offensive in mid-October. More than 50 people have been killed in the area in a little over a week.
Militants staged a pair of attacks against anti-Taliban figures in northwestern Pakistan on Sunday, killing one of the men.
The government has supplemented its military campaigns by helping tribal leaders and local government officials set up militias to battle the Taliban. The militias, known as lashkars, have been compared to Iraq's Awakening Councils, which helped U.S. forces turn the tide against al Qaeda there.
As in Iraq, militants in Pakistan have targeted the leaders of such groups.
A group of militants opened fire on the house of an elder, Malik Sher Zaman, in the Bajur tribal region around midnight on Sunday, killing him several months after he signed an agreement with the government to battle the Taliban, said senior local official Abdul Malik. The militants blew up part of his house in the Mamund area after the attack, he said.
Several hours later, more than a dozen militants opened fire on the house of an anti-Taliban mayor outside Peshawar, but security guards repelled the attack, killing three of the assailants, said police official Nabi Shah.
The militants who initiated the attack against Mayor Mohammad Fahim Khan's house in Bazid Khel town, some 10 miles (15 kilometers) south of Peshawar, had disguised themselves by donning burqas, the all-encompassing garments traditionally worn by Muslim women, said Shah.
"Seeing three burqa-clad women early in the morning, Fahim Khan's security guards challenged them, and the men threw away their disguise and opened fire," Shah said. "But the guards were alert and they retaliated quickly."
The guards killed the three militants, but several others joined the fight, Shah said. The two groups waged a gunbattle before the remaining militants fled, he said.
A growing number of recent attacks in Pakistan have targeted civilians, including a suicide bombing at a market in Peshawar in late October that killed 112 people, the deadliest attack in Pakistan in more than two years.
No group has claimed responsibility for the attacks targeting public places, but Pakistani officials have blamed the Taliban.
In a video released Sunday, the group denied the allegations, saying it was focused on attacking the Pakistani government and did not believe in killing civilians.
Repeating conspiracy theories that have appeared in local media, Taliban spokesman Azam Tariq blamed the recent attacks, including a suicide bombing at an Islamic university in the capital, on the Pakistani government and the private security firm formerly known as Blackwater.
"The dirty Pakistani intelligence agencies, for the sake of creating mistrust and hatred among people against the Taliban, are carrying out blasts at places like the Islamic university, Islamabad, and the Khyber bazaar, Peshawar," said Tariq.
The video, which was posted on YouTube, carried the logo of al Qaeda's media wing, As-Sahab. It was the first time the Taliban spokesman has appeared in an As-Sahab video, showing the growing links between the two groups.
By denying responsibility for killing civilians, the Taliban could make it more difficult for the government to convert public anger into greater support for the South Waziristan offensive and other efforts to crack down on militants.