Fire crews were called to Perth Prison after an package was caught in the fence.
The Scottish Fire and Rescue Service rushed to the scene on “blues and twos” after being asked to attend the facility by Police Scotland at 12.22pm.
Police Scotland declined to elaborate on the nature of the incident.
However one eyewitness said an attempt had been made to get a package over the prison’s barbed wire-topped wall.
“It looks like someone’s tried to lob something over the wall and it’s got caught in the fence,” he said.