Health chiefs have demanded answers over how a patient came to fall 30ft from a three-storey building at Royal Preston Hospital.
The 19-year-old woman suffered severe back injuries in the incident at the site in Sharoe Green Lane, Fulwood, Preston.
Hospital bosses have now launched an investigation into how the woman came to be on the roof.
Staff from the A&E department were called to the scene in the hospital grounds, opposite the site’s accommodation blocks, at around 6.30pm on Thursday, October 17.
Police, who received a ‘concern for safety’ call from a worried member of the public at around 6.20pm, said the woman was conscious, but complained of severe back pain.
She was put on a spinal board by paramedics before being transported a short distance by ambulance to the emergency ward.
North West Ambulance Service said the woman had suffered lower back, upper back and possible pelvic injuries. Firefighters were also called to the scene.
The Evening Post understands the patient is still receiving treatment at the hospital.
Miles Timperley, director of facilities and estates for Lancashire Teaching Hospitals NHS Foundation Trust, said: “We have robust procedures and systems in place that restrict access to roofs and control unauthorised access.
“An internal investigation is ongoing and the outcome of that investigation will be reviewed.”
Coun Margaret McManus, who represents Sharoe Green ward, said she was deeply concerned by the incident.
She said: “I’m appalled that anything like this could have happened, particularly in a hospital.
“Royal Preston Hospital has a very good record of safety and most of the staff are very, very caring.
“I want to know how the person got on the roof. How on earth could anybody have got on the roof without being detected?
“People have to be monitored on the wards.”
Healthwatch Lancashire, the county’s new health watchdog, said it had contacted the trust to find out more about what had happened.
Leslie Forsyth, chief executive of the independent consumer champion, said: “We will be keeping a watchful eye on this and will be interested to see what the outcome of their own inquiry into what went on is, and anything that arises from that to improve patient safety.”