A bomb ripped through a public park packed with families celebrating Easter in the Pakistani city of Lahore on Sunday, killing at least 65 people and wounding more than 250 others, most of them women and children, officials said.

A suicide bomber set off an explosive vest packed with ball bearings in a parking lot near amusement park rides in Gulshan-e-Iqbal Park, located in a mostly residential neighborhood of western Lahore.

A splinter group of the Pakistani Taliban claimed responsibility for the bombing, which it said was aimed at Christians celebrating the Easter holiday.

Pakistan, an overwhelmingly Muslim nation, has a small Christian minority. Officials said they had not confirmed that Christians were the target.

The bloodshed overwhelmed rescue agencies in Pakistan’s second-largest city. Victims jammed Lahore’s hospitals, spilling into the corridors where doctors and medical staff raced to treat them. Many more victims arrived at medical facilities in taxis or motorized rickshaws because ambulances were full.

Pakistani security officials condemned the attack as “savage,” and said intelligence agencies would find the perpetrators. The chief minister of Punjab state announced three days of official mourning.

It was deadliest attack in Pakistan since the December 2014 massacre at an army-run school in which 143 people died, most of them children, and marked a devastating new turn in militant violence against Pakistani civilians.

The Pakistani Taliban, a federation of insurgent groups that aims to overthrow the Pakistani government, continues to mount brazen attacks despite a nearly two-year military offensive against militant hideouts in the country’s northern tribal belt.

The group that claimed responsibility for Sunday’s blast, the Jamaat-ul-Ahrar faction of the Pakistani Taliban, split with the federation in 2014 and is believed to have carried out a major attack in Lahore later that year that killed at least 60 people near the Indian border.

In January, a separate splinter faction of the Pakistani Taliban claimed responsibility for a raid on a university in the northeastern town of Peshawar that killed 21, many of them students who were shot at close range in their dormitories.

Christians, who make up less than 2 percent of Pakistan’s 182 million people, have frequently been targeted by Pakistani extremist groups. In 2013, 75 Christians were killed in a suicide bombing at a church in the northeastern city of Peshawar.

Lahore, a cosmopolitan city of more than 12 million and the seat of power in Prime Minister Nawaz Sharif’s home state of Punjab, has been less affected by militant violence than other major Pakistani cities. The park where the attack occurred sits on nearly 70 acres and includes a large man-made lake, zip-lines and a rock-climbing wall.

Since 2003, more than 21,000 Pakistani civilians have been killed in militant violence, according to statistics by the South Asia Terrorism Portal, an independent group that tracks the fatalities.