Peshawar, Pakistan ? A suicide bomber detonated his explosives-packed vehicle in a crowd of people watching a volleyball tournament in northwest Pakistan, killing 88 people in the deadliest attack in the country in more than two months.

The attack in Lakki Marwat city on Friday appeared to be retaliation against residents who formed militias to drive militants out of the area and a meeting of anti-Taliban leaders being held nearby may have been the actual target, police said.

The blast underscores the difficulty Pakistan has had in stopping militants whose reach extends far beyond Pakistan’s lawless tribal belt and who appear increasingly willing to strike civilians as well as security forces.

The attack was not far from South Waziristan, where the army is waging an offensive against the Pakistani Taliban. That operation has provoked apparent reprisal attacks that have killed more than 500 people since October.

No group claimed responsibility for Friday’s blast, but that is not uncommon when large numbers of civilians are killed.

“The locality has been a hub of militants. Locals set up a militia and expelled the militants from this area. This attack seems to be reaction to their expulsion,” local police chief Ayub Khan told reporters.

Khan said an anti-Taliban meeting of local tribal elders in a mosque close to the field where the tournament was being held was the real target of the attack, but the driver failed to reach it.

The bomber set off some 550 pounds of high-intensity explosives loaded in the car at the field, which lies in a congested neighborhood, Khan said.

Local police official Tajammal Shah said today 88 people were dead and 50 wounded. He said eight children, six paramilitary troops and two police were among the dead.

Omar Gull, 35, a paramilitary soldier who was wounded, told an AP photographer at a nearby hospital that the attacker drove the vehicle recklessly into the crowd.

“People were just trying to understand what’s happening when the bomb went off,” he said. “It was then chaos. It was smoke, dust and cries.”

Another police official, Habib Khan, said some 300 people were on the field when the incident took place.

“We had security there. We had it for the meeting, and for the tournament,” Ayub Khan told The Associated Press by phone.

Regional Information Minister Mian Iftikhar Hussain reiterated the government’s resolve to target militants wherever they may be, saying “we need to be more offensive to fight them.”

The attack was the deadliest since a car bomb killed 112 people at a crowded market in Peshawar on Oct. 28.

Karachi, the country’s largest city, came to a virtual standstill Friday after religious and political leaders called for a general strike to protest a bombing that killed 44 people and subsequent riots.

The city’s major markets, stores and business centers were closed, along with financial institutions that had already planned to shut for New Year’s Day.

Public transportation was halted and gas stations were closed.