Kids went partially through an asbestos roof while climbing on an industrial building in Castledawson.
Police are appealing to parents and teachers to alert young people of the dangers.
In a social media post Magherafelt PSNI said they could have been delivering deaths messages
They said: "Kids just over the age of 10 decided to climb on the roof of an industrial building in Castledawson.
"The asbestos roof - over 30ft off the ground - gave way. The kids went partially through the roof.
"Now we aren’t going to be all holier than thou and pretend we didn’t climb trees or explore places when we were younger, but parents we would strongly ask you have a word with your kids. Teachers you can help too and tell your class.
"Aside from the fact these places are private property and there are a rake of trespass and criminal damage offences, explain to them the absolute craziness of climbing on roofs - old asbestos roofs are especially brittle and can just about take the weight of a cat. A child has no chance.
"Spread the word and lets not have a repeat of this one, that was far too close for comfort."