Police say the death toll has hit 75 in a suicide car bombing at a volleyball tournament in northwest Pakistan.
Local police chief Ayub Khan says Friday's blast in Lakki Marwat was retaliation for locals' attempts to expel militants by setting up their own militia. He says 75 people are confirmed dead.
He says more than 60 people are being treated at local hospitals.
Lakki Marwat lies close to North and South Waziristan, two tribal regions where militants have proliferated.
Since the army launched a ground offensive in South Waziristan in October, a slew of bombings have plagued Pakistan and killed more than 500 people.
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 in Lakki Marwat city 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.
In some parts of the northwest, residents have taken matters into their own hands, starting militias to beat back insurgents. Police said Friday's bombing was possible revenge for such efforts in Lakki Marwat.
No group claimed responsibility, 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.
He said the bomber drove a vehicle loaded with 550 pounds (250 kilograms) of high-intensity explosives onto the field, which lies in a congested neighborhood. Some nearby houses collapsed, and "we fear that some 10 or so people might have been trapped in the rubble," Khan said.
In addition, a group of local tribal elders were holding a meeting at a mosque nearby. The mosque was damaged and some people there died, he said.
Another police official, Habib Khan, said at least 32 people died and more than 70 were wounded. He said some 300 people were on the field when the incident took place.
Regional Information Minister Mian Iftikhar Hussain said the death toll may jump to more than 50. "We have 32 bodies, but there are body parts lying in the rubble," he said.
Private TV footage taken from a hospital afterward showed bloodied men on stretchers, looking dazed as relatives hovered nearby.
Hussain reiterated the government's resolve to target militants wherever they may be, saying "we need to be more offensive to fight them."
Also Friday, a suspected U.S. missile struck a car carrying alleged militants in North Waziristan tribal region, killing three men, two intelligence officials said. It was the second such strike in less than a day.
The strikes are part of the U.S. campaign to eliminate high-value militant targets that use Pakistan as a safe haven to plan attacks in neighboring Afghanistan and on the West.
Friday's strike happened near Mir Ali, a major town in the region, two intelligence officials said on condition of anonymity because they were not authorized to speak on the record. Shortly afterward, Taliban fighters arrived at the scene of the attack in the village of Ghundi and moved the bodies to an undisclosed location, the officials said.
Thursday's missile strike was also near Mir Ali, hitting a house and killing three people.
U.S. officials rarely discuss the strikes, and Pakistan publicly condemns them, though it is widely believed to aid them secretly.
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.
Monday's bombing occurred in the midst of a procession of minority Shiite Muslims during the Islamic holy month of Muharram. Afterward, angry protesters went on a rampage, setting fires to about 2,000 stores that took three days to completely put out.
Interior Minister Rehman Malik, on a visit to Karachi, said investigators were still determining if the attack was a suicide bombing.
He also questioned the claim of a purported Taliban spokesman, Asmatullah Shaheen, that the militant group was behind the attack. Local news reports on Friday quoted a more prominent Taliban spokesman, Azam Tariq, as denying that the Pakistani Taliban's central leadership had approved the attack, though he did not rule out the possibility that Shaheen's group had carried it out without approval.
Elsewhere in the northwest, a roadside bomb exploded near a car in the Bajur tribal region, killing an anti-Taliban tribal elder and five of his family members, said Nasib Shah, a local government official.
Bajur was the focus of a 2008-09 army offensive but still suffers some militant violence. Tribal leaders who support the government against the Taliban are frequent targets of attacks.
This program aired on January 1, 2010. The audio for this program is not available.