A violation of safety norms could have been responsible for the explosion at NTPC’s Unchahar plant in Rae Bareli on Wednesday, The Indian Express reported. The toll in the explosion, one of the country’s worst industrial accidents in years, rose to 32 on Friday, PTI reported. More than 100 people have been injured.

NTPC, formerly known as the National Power Thermal Corporation, has formed a three-member committee to investigate whether safety norms were violated and what caused the blast. The National Human Rights Commission had asked for a report on accident.

The corporation did not accept or deny the claim, and told The Indian Express: “…we feel it is too premature for us to conclude the exact causes, for which a committee has been constituted. We request you to bear with us and not go by hearsay and unauthenticated information being circulated around.”

Rods are often used to remove ash blocks from the funnel-shaped bottom end of boilers, even when they are in operation. Coal-fired plants across the country resort to similar violations, The Indian Express reported. The explosion happened when pressure from the furnace in unit no. 6 increased, the report said, citing initial observations from sources.

“The unit was then running at a load of around 200 MW, lower than usual because there was some hindrance in the ash coming out,” NTPC Regional Executive Director (North) Ravindra Rathee was quoted as saying.

Fans meant to maintain pressure inside the boiler could have malfunctioned, according to The Times of India. This might have led to pressure inside the boiler increasing by 40 times what was normal. “There should be a fine balance in the air movement inside the boiler for proper pressure,” the regional director told The Times of India. “In case of any imbalance, the system trips and fans start reducing the pressure. In this case it does not seem to have happened.”