Yobs ripped up a man hole cover at an Eastwood park, leaving a dangerous 30ft deep drop open for disaster.
They tried to steal the cast iron cover at Coronation Park some time on Monday night, but failed.
Police said the thieves only dislodged the cover, which pushed it further down the shaft.
PCSO Derek Kershaw said: “This left the hole open for a small child or dog, or even an adult, to suffer serious injury.”
The danger was reported to police by a dog walker on Tuesday morning.