The suicide bomb exploded near the children's rides in a bustling park as Christians were enjoying Easter. Many of the victims were women and children.

The death toll rose to 72 on Monday, with 29 children among those killed, said rescue spokeswoman Deeba Shahbaz, adding that around 340 people were injured by the blast.

Tanvir Shahzad, DW's Lahore correspondent, said that Pakistani Christians were participating in festivities to mark Easter.

"There were more people in the park than usual because of the holiday. The country's Christians were also celebrating Easter in the park," Shahzad said. Christians make up an estimated 1.6 percent of the population.

A faction of the Pakistani Taliban, the militant Jamaat-ul-Ahrar, claimed responsibility for the bombing and threatened to strike again.

"The target was Christians," said Jamaat-ul-Ahrar spokesman Ehsanullah Ehsan. "We want to send this message to Prime Minister Nawaz Sharif that we have entered Lahore."

A senior police official told DW that security forces were bolstering security across Lahore, the capital of Punjab and power hub for the prime minister.

"We are in a state of war. We have beefed up security in Lahore. The terrorists wanted to target innocent people," Pakistani deputy inspector general of police, Haider Ashraf, told DW.

It was not immediately known how many of the dead and injured were from the Christian community, said Ashraf. He added that the majority of those killed by the blast were Muslims.

Three days of mourning have been announced in Punjab province, of which Lahore is the capital, with the national flag flying at half-mast.

In response to the attacks, Facebook activated its security check system for users to let friends and family members know they were safe. However, a glitch in the system sent notifications to people all over the world. Although the company apologized for the error, some users said the glitch meant news of the attacks spread faster than usual.

Pakistan's Nobel Peace Prize winner Malala Yousafzai responded to the attacks in a statement on Twitter which said: "Pakistan and the world must unite. Every life is precious and must be respected and protected."

Pakistan has been the target of militant attacks for years, especially in the restless tribal region along the border with Afghanistan.

The government has stepped up operations against militants following a Taliban attack on a military-run school in Peshawar in December 2014 that killed 134 children.

While the Pakistani Taliban and Jamaat-ul-Ahrar have carried out numerous attacks against security forces, the government and Western targets, they have also often targeted Christians and Shiite Muslims.

Twin suicide attacks against two churches in Lahore killed 17 people in March last year. The attacks, which were claimed by Jamaat-ul-Ahrar, triggered two days of rioting by thousands of Christians.

Pakistan's ISI intelligence service has long been accused of supporting and turning a blind eye to Islamic extremists to pursue security objectives in Afghanistan and counter regional rival India.

rs, cw/gsw (AFP, AP, dpa, Reuters)