The fire ignited roofing materials which had fallen down as the result of the explosion.The operator, who was outside the plant when the explosion occurred, pulled the emergency switch which shut down all the compressors. Although in a dazed condition he then checked in the motor room that all the motors had stopped. He was subsequently taken to hospital where he was found to have no physical injuries but was moderately shocked. The fire alarm was raised by the Gatekeeper who had heard the explosion and seen flames and smoke in the vicinity of the hydrogen plant. The works fire team were quickly on the scene but were advised not to extinguish the fire while hydrogen was still escaping, to prevent the likelihood of further explosion.The supply of hydrogen to the compression plant was cut off and the plant was electrically isolated before the arrival of the County Brigade. By the time they arrived, (within about seven minutes), the flow of hydrogen had stopped and the fire was quickly extinguished using water.