A man was taken to hospital after falling 20ft through a roof at the former Camelot theme park.
Police and paramedics were called to the disused site on Park Hall Road, Charnock Richard, at 7.35pm yesterday.
The 20-year-old man had fallen through a roof onto a concrete floor, landing on his back.
He was taken to Royal Preston Hospital for treatment to arm and back injuries.
It is understood his injuries were not life-threatening.
The site has been derelict since 2012 when the theme park closed.
Plans to build a 420-home housing estate there were rejected earlier this year.