A suicide bomber in Pakistan killed more than 50 people, the New York Times reported Sunday. At least 55 were dead and more than 120 injured after the deadly explosion occurred in Wagah, a checkpoint in between in eastern Pakistan and India.

The person responsible is believed to have been in his early 20s. He detonated his vest during an elaborate flag-lowering ceremony as the border closes. Thousands of people from both sides, including women and children, were in attendance.

A group of the Pakistani Taliban reportedly took responsibility for the bombing.

“This is a continuation of our jihad for the implementation of an Islamic system in Pakistan,” Ehsanullah Ehsan, a spokesman for the group, Jamaat-e-Ahrar, said, according to the Times. He added the group would continue to attack “the pillars of the infidel system” now governing Pakistan.

A witness, who is an intelligence official, said the blast happened after the bomber approached a restaurant. "I rushed to the scene and saw scattered bodies, injured men, women and children and smashed cars," the official told Reuters.

Indian Prime Minister Narendra Modi condemned the attack as a "dastardly act of terrorism,” the BBC wrote. Pakistani opposition politician Imran Khan also called the explosion an “act of terrorism.”

India and Pakistan have fought three wars against each other and are in a battle over the region of Kashmir, which both sides claim.

Follow me on Twitter @mariamzzarella