TISZAÚJVÁROS, Hungary (AP) — An explosion at a petrochemical plant in Hungary on Friday killed one person and injured several others, according to a statement by Hungarian energy company Mol Group, which owns the plant.

The explosion in Tiszaújváros, in eastern Hungary, occurred during a restart of the plant following maintenance, Prime Minister Péter Magyar said in a post on social media. He added that seven people had suffered burn injuries during the blast.

Five helicopters transported the injured to hospitals in the cities of Miskolc and Debrecen, according to Minister of Economy and Energy István Kapitány. In a social media post, Kapitány wrote that a disaster response mobile laboratory did not detect any concentrations of hazardous materials above the threshold limit.

Both Kapitány and Mol CEO Zsolt Hernádi are en route to the site of the explosion, Magyar said.

“We express our sincere condolences to the family of the deceased and wish the injured a speedy recovery,” Magyar wrote on Facebook.

A spokesperson for the regional disaster management authority told state news agency MTI that the fire caused by the explosion at the plant had been extinguished. Dávid Dojcsák said that cleanup operations were still underway and emergency units were securing the site.