At least 52 people were killed on Friday in what officials believed was a suicide attack at a religious gathering in southwest Pakistan, the latest sign of the country’s deteriorating security situation.

The blast occurred around midday in Mastung, a district in Balochistan Province. It targeted a procession of hundreds of people who had gathered for Eid-e-Milad-un-Nabi, a holiday celebrating the birthday of the Prophet Muhammad.

The death toll was confirmed by Abdul Rasheed Shahi, Mastung’s district health officer. He said at least 50 more people had been injured.

“Due to the power of the explosion, several people gathered there died instantly, and many others suffered injuries,” said Javed Lehri, a local police officer. “We are investigating, but it seems it was a suicide attack.”

No group has yet claimed responsibility for the blast, officials said. Among the victims was a police officer.

The blast was the latest attack to rattle Pakistan, where militant groups have become more active over the past two years after finding safe haven in neighboring Afghanistan under the Taliban administration.

The Pakistani Taliban, a militant group with close ties to the Afghan Taliban that opposes the Pakistani government, and the Islamic State affiliate in the region have carried out some of the country’s deadliest attacks in that time. The Islamic State affiliate, known as the Islamic State Khorasan, or ISIS-K, has carried out attacks in Mastung district in recent years.

Videos from the aftermath of the attack circulating on social media showed hundreds of people gathered around bodies splayed across pools of blood.

“Rescue teams have been dispatched to Mastung,” Jan Achakzai, provincial information minister, said. Critically injured people were being transferred to the provincial capital, Quetta, around 20 miles away, he added.