Dozens of children and mothers are among the victims of the Easter suicide bombing in a Lahore public park in which at least 72 people have been killed.
A breakaway faction of the Pakistani Taliban has claimed responsibility for the attack in Gulshan Iqbal Park.
Even though the group said it had deliberately targeted Christians "celebrating Easter", it has emerged that most of those killed in Lahore were Muslims.
Of the dead, 14 have been identified as Christians, according to Lahore Police Superintendent Mohammed Iqbal.
Pakistani authorities have launched a hunt for those behind the bombing - the deadliest on Pakistan soil since the Peshawar school massacre in December 2010 in which 134 children were slaughtered.
Some reports have placed the number of children killed on Sunday at 29. Many of those injured are in a serious condition, leading to fears the death toll could rise still further.
Blasts hit Lahore
Punjab's chief minister, Shahbaz Sharif, has announced three days of mourning and pledged to bring the perpetrators to justice.
The explosion took place near the main gate of the park, close to the swings and rides of the children's play area.
Mohammad Ali, a student who lives nearby, said he saw many children killed.
"I saw body parts everywhere, especially those of young children," he told The Guardian.
"It was quite haunting, as many of the children's rides were still operating, while there were dead bodies lying all around them."
Parents were seen searching for their children among the debris in the aftermath of the blast.
Jamaat-ul-Ahrar, a splinter group of the Taliban, has been waging an insurgency in Pakistan in affiliation with the Taliban in Afghanistan, where militants have been trying to regain power since being toppled by the US and allies in 2001.
Yet Lahore has seen relatively few attacks compared to areas close to the Afghan border.
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The Taliban's leadership has seemed fractured in recent months. After an attack on a school in January, on of the group's official spokesperson denied involvement but another claimed responsibility.
At the time, a faction commander said the group was targeting youngsters who were being "prepared" for government service and would continue to target education institutions.
After this most recent attack, Jamaat-ul-Ahrar has also said it will continue its insurgency.
"This is a message to the Pakistani prime minister that we have arrived in Punjab," a spokesman said.
Pakistan's army chief, General Raheel Sharif, has convened an emergency meeting of the country's intelligence agencies to begin to track down those responsible for the attacks.
Salman Rafiq, a health adviser to the Punjab government, urged people to donate blood, saying many of the wounded are in a critical condition.