Occupants of a car which crashed into HMP Leeds at Armley fled the scene before police arrived.
West Yorkshire Police were called to Hall Lane at 9.10pm on Friday night to reports of a car crashing into the outer prison wall.
One man was taken to hospital with what were believed to be serious but not life threatening injuries.
It is understood the driver and possibly one or two more passengers left the scene before police arrived.
Enquiries are ongoing.
Anyone with any information is asked to contact police on 101 quoting log 1833 of April 5.