Victims of the attack were taken to nearby hospitals
At least 88 people have been killed by a suicide bomb attack at a volleyball court in the troubled north-west of Pakistan, local police say.
Police chief Ayub Khan said the bomber drove towards a field where people were watching a match, before detonating a load of high-intensity explosives.
The attack happened near Lakki Marwat, close to North and South Waziristan.
The Pakistani army has been conducting a campaign against the Taliban in the tribal areas since October.
The number of people killed in militant attacks in Pakistan is fast approaching 600 in just three months.
Militants have attacked both "hard" targets, including army or intelligence offices, and "soft" ones such as markets or the crowd that was hit in Friday's bombing.
The latest attack killed more people than any other since a bombing at a market in Peshawar left some 120 people dead on 28 October.
Dozens of people were reported to be injured in Friday's attack. Several buildings collapsed, trapping people under rubble.
By Aleem Maqbool, BBC News, Islamabad
The Pakistani army's operation in South Waziristan, which began in October, was billed as the turning point in the country's fight against the Taliban.
The military says things have gone extremely well, and that it now controls most of that former Taliban stronghold.
But the period since the offensive started has coincided with a massive upsurge in militant attacks that has now claimed the lives of over 600 people right across the country.
The government says the hitting of soft civilian targets, as the one in Lakki Marwat, is proof that the militants are getting desperate, and know the authorities have the upper hand. Most Pakistanis will be unconvinced of that.
"The villagers were watching the match between the two village teams when the bomber rashly drove his double-cabin pick-up vehicle into them and blew it up," district police chief Ayub Khan told AFP news agency.
"Every day there are volleyball matches taking place," said one man who was injured in the explosion.
"Today, all the people had gathered together watching, when suddenly a [Mitsubishi] Pajero came in the middle of the field and blew up."
Mr Khan told reporters the attack may have been retaliation for attempts by locals to expel militants.
"The locality has been a hub of militants," he said.
"Locals set up a militia and expelled the militants from this area. This attack seems to be a reaction to their expulsion."
The BBC's Aleem Maqbool reports from Islamabad that among those killed are believed to be members of a local peace committee who have been campaigning for an end to the violence.
Mushtaq Marwat, a member of the group, told Pakistan's Geo TV that the attack occurred as the committee was meeting in a nearby mosque.
"Suddenly there was a huge blast. We went out and saw bodies and injured people everywhere," he said.
Other people recalled seeing a bright flash before hearing an ear-piercing explosion.
One witness said that later, people were using vehicle headlights to search for victims in the dark.
Khalid Israr, a senior regional official, told Reuters news agency that the military had been deployed to help local authorities.
"It is a small village with very few rescue facilities. Rescue equipment is being sent there from other places."
North and South Waziristan form a lethal militant belt from where insurgents have launched attacks across north-west Pakistan as well as into parts of eastern Afghanistan.
Our correspondent says it had been feared that while the army was congratulating itself on its campaign, militants had simply escaped to neighbouring areas such as the one where Friday's attack happened.
The attack came as a general strike was held in Karachi, Pakistan's commercial capital, in protest against a bombing there on Monday and riots that followed.
The bombing, which killed at least 43 people, targeted a Shia Muslim march and was claimed by the Taliban.
RECENT MILITANT ATTACKS IN PAKISTAN
Lakki Marwat, 1 January: At least 60 killed in bombing at volleyball pitch
Karachi, 28 December: At least 43 killed in attack on Shia Muslim march
Dera Ghazi Khan, 15 December: At least 27 killed in bomb attack on market
Multan, 8 December: Intelligence agency office attacked - at least 12 killed
Peshawar: Many recent attacks - 28 October market bombing killed about 120
Lahore: Targeted several times - market bombs killed 50 on 7 December
Rawalpindi: Several recent attacks, including one at a mosque on 4 December in which 35 died
Islamabad: Security tightened after series of attacks - 20 October bombing killed nine at International Islamic University
Charsadda, 10 November: Car bomb kills 34 and wounds 100