The death toll from a massive suicide bombing that targeted an election rally for a pro-Taliban cleric rose to 54 on Monday as Pakistan held funerals and the government vowed to hunt down those behind the attack.

No one immediately claimed responsibility for Sunday’s bombing, which also wounded nearly 200 people. Police said their initial investigation suggested that the Islamic State group’s regional affiliate could be responsible.

The victims were attending a rally organized by the Jamiat Ulema Islam party, headed by hard-line cleric and politician Fazlur Rehman. He did not attend the rally, held under a large tent close to a market in Bajur, a district in Khyber Pakhtunkhwa province that borders Afghanistan.

Rehman, who has long supported Afghanistan’s Taliban government, escaped at least two known bomb attacks in 2011 and 2014, when bombings damaged his car at rallies.

Victims of the bombing were buried in Bajur on Monday.

As condolences continued to pour in from across the country, dozens of people who received minor injuries were discharged from hospitals, while the critically wounded were taken to the provincial capital of Peshawar by army helicopters. The death toll continued to rise as critically wounded people died in hospitals, physician Gul Naseeb said.