TRESPASSING teenagers are believed to have injured themselves climbing out of a vacant office block window.

Concerned onlookers spotted the youngsters clambering out of a small first floor hinged window at Miller House in Market Street, Farnworth, at 7pm on Saturday.

Witness Andrew Nicholson said: "We were in the Wellington pub having a birthday drink with a friend when I looked out of the window to see movement in Miller House across the road, which has been derelict for a while.

"As I was watching, to my horror young people started to climb from the window to land on the awning over the front door.

"Some of them landed on the parapet then safely if clumsily dropped to the ground while others, especially two girls, lost their grip on the window, bounced off the parapet and landed horrifically."

The partner of Mr Nicholson went outside to speak to the group, one of whom said she came from the New Bury area of Farnworth.

Mr Nicholson explained: "My partner tried to talk to one of the girls who was holding her hip and said she couldn't breathe, but her two young male friends dragged her off.

"She was limping and obviously in a lot of pain."

Mr Nicholson uploaded photographs of the trespassers, believed to be two boys and two girls dressed mainly in black, on social media to highlight their actions and to alert parents.

He wrote: "If anyone in the Farnworth area have their kids coming home injured tonight it's because they all for some reason jumped out of the first storey window of the old DSS building window earlier and some lost their footing and crashed to the floor."

Mr Nicholson said he shared the images because he "hopes it stops any more children from being injured".

Local police were alerted to the incident.

Miller House most recently housed ECX Training, a company offering basic skills and technical courses.