A group of youths have tried to set alight a Scunthorpe community centre while a keep fit class was being held inside.
The incident happened at the Rowland Road centre between 7.30pm and 8.15pm on Thursday, August 18.
It is believed a group of around five youths, aged between 16 and 18, climbed onto the roof and attempted to set it alight.
Sergeant James Main said: “We are treating this incident extremely seriously. Ten to 15 people were inside the centre at the time.
“Luckily, no one was hurt as a result of their actions, but this could have easily resulted in someone being seriously injured or even killed.
“I would appeal for anyone who was in the area at the time to get in touch so that we can find those responsible for this incident as quickly as possible.”
Any witnesses, including those attending the class, should call Humberside Police on 101 quoting log number 621 of August 18.
Alternatively, call Crimestoppers anonymously on 0800 555111.