The toll from an explosion in a mosque in Bangladesh rose to 24, after three more persons succumbed to their injuries on Sunday, Daily Star reported, quoting the Sheikh Hasina National Institute of Burn and Plastic Surgery in Dhaka.

The explosion, which fire service officials suspect was caused by leakage from a pipeline, took place at the Baitus Salah Jame Mosque in Narayanganj district on Friday night. The blast had triggered a fire in the premises as worshipers were about to finish their prayers.

At least 37 people were admitted to the state-run specialised burn and plastic-surgery hospital in Dhaka, where 24 subsequently died. Samanta Lal Sen, coordinator of the burn unit, on Saturday said among the dead is a seven-year-old boy, according to Al Jazeera. Dozens were injured with severe 90% burns as the impact of the blast caused at least six air conditioners to also explode.

Fire officials said gas that accumulated from a leak in a pipeline running underneath the mosque likely triggered the explosion. “A pipeline of Titas Gas passes beneath the mosque,” Narayanganj Fire Service’s Deputy Assistant Director Abdullah Al Arefin had said on Saturday. “We are suspecting that gas had leaked from the pipeline and accumulated inside as the windows were closed. The explosion was probably triggered due to sparks when someone tried to switch the ACs or fans on or off.”

Four separate inquiry committees – by Narayanganj district administration, Fire Service, Titas Gas Transmission and Distribution Company Limited, and Dhaka Power Distribution Company – have been formed to investigate the incident, according to the Dhaka Tribune.