Firefighters were called to Sheffield's derelict former ski village to deal with another blaze.
Plumes of thick black smoke could be seen for miles across the city when the blaze broke out on Friday afternoon.
Firefighters who responded to calls about the blaze found the old derelict pump house alight.
A bonfire had been lit nearby and the flames had spread.
The fire is not being treated as malicious.
Arson attacks have been common at the site of the former ski village off Vale Road, Parkwood Springs, since it was torched in 2012.