Youths stole alcohol-based hand-wash from the back of ambulances to start a fire in a skate park.
Firefighters say youths managed to sneak into the back of ambulances outside A&E at St Helier hospital so they could steal the hand sanitiser.
They then took the bottles to the nearby Rosehill skate park where they started a fire on one of the ramps.
Firefighters from Sutton were called to the scene just before 9pm last night after a passer-by spotted the fire and saw a gang of youths running away.
A Sutton firefighter said: "The fire was relatively small but as we were putting it out it became apparent that they used alcohol-based hand cleansers to start it.
"We thought they must have taken them from the hospital so we went over there but it turns out they have been taking them from the backs of ambulances as they are unloading people."
Police and hospital security have been made aware of the incident and are investigating. The fire caused only minor damage to the skate ramp.
If you have information about the incident, you can call police on 101 or the charity Crimestoppers on 0800 555 111.