At least 69 people have been killed and scores injured in an explosion at a public park in the eastern Pakistani city of Lahore, officials say.
The park was crowded with families, some celebrating Easter. Many victims are said to be women and children.
Police told the BBC it appeared to be a suicide bomb. A Pakistan Taliban faction said it carried out the attack.
Pakistan's president has condemned the blast and the regional government has announced three days of mourning.
All the major hospitals in the area were put on an emergency footing after the blast early on Sunday evening.
The explosion appears to have been at the main gate to the Gulshan-e-Iqbal park in an area where cars are usually left - and a short distance from the children's swings.
One eyewitness said there was chaos, with a stampede starting and children separated from their parents in the rush to escape.
Another man told Pakistan's Geo TV station he was heading towards a fairground ride with his wife and two children when he heard a huge bang and all four of them were thrown to the floor.
Hasan Imran, 30, a local resident who had gone to the park for a walk told Reuters: "When the blast occurred, the flames were so high they reached above the trees and I saw bodies flying in the air."
The agency also reported that the army was called in to control crowds outside the park.
According to Lahore's deputy commissioner, Mohammad Usman, the number of injured was 193.
Facebook has activated its feature for people in Lahore to mark themselves as safe, as news of the blast spread.
Lahore is the capital of Punjab, Pakistan's largest and wealthiest province and the political powerbase of Prime Minister Nawaz Sharif.
Pakistan Taliban splinter group Jamaat-ul-Ahrar told local and Western media it was behind the attack.
"We claim responsibility for the attack on Christians as they were celebrating Easter," spokesperson Ehansullah Ehsan told Pakistan's Express Tribune.
Pakistan has suffered regular incidents of Taliban-related violence, sectarian strife and criminal gang activity.
Meanwhile in the capital, Islamabad, police fired tear gas at thousands of protesters who marched in support of Islamist gunman Mumtaz Qadri, whom they see as a religious hero.
Qadri was hanged last month for the murder of Punjab governor Salman Taseer five years ago.
Mr Taseer had defended a Christian woman jailed on blasphemy charges.