Merseyside Police say they are at Parr Swimming Baths this evening after a child fell through the roof.
A spokesman for the force said: "We are currently attending to an incident at Parr Swimming Baths in St Helens this evening, Sunday, 23 June.
"At around 6.20pm, emergency services were called to the premises following reports that three youths had been seen on the roof before one of them, a 12-year old boy, fell through.
"He has been taken to hospital in a serious condition where his injuries will be assessed. Enquires are ongoing to establish the full circumstances.
"Anyone who witnessed the incident, or has any information, is asked to contact @MerPolCC, 101 quoting ref. 822 or @CrimestoppersUK."