A 12-year-old boy has died after falling through the roof of a derelict factory.
The boy was found critically injured inside the Aida Bliss building in Derby, just after 19:30 BST on Friday.
He was taken to hospital where he was later pronounced dead.
Police said he had been at the factory in City Road, Chester Green, with two friends who had been left “understandably distraught” by what happened.
The building was used to make metal stamping presses, but since closing in 2004 it has attracted people inside to take photos and videos they post online.
Officers have appealed for potential witnesses to speak to them “urgently”.
They believe there may have been other youngsters inside the factory who were not known to the group.
Ch Supt Jim Allen, of Derbyshire Police, said: “This is a tragic incident and our thoughts and sympathies go out to the young boy’s family.
“If you were in the building at the time, you will not be in any trouble – we just need to speak to you as a witness as soon as possible, so please call us now.”
He said specially trained officers and staff are supporting the boy’s family “at this unimaginably difficult time”.
Ch Supt Allen also urged anyone who was in the area or passing by at the time to contact police.
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