A pavilion in woodland was partly damaged when a moped was set on fire in a suspected arson.
Firefighters were called to the former Orchard Hill hospital site in Carshalton at 9.40pm on Tuesday.
A firefighter said a moped had been found "torched" next to the pavilion.
Firefighters from Wallington and Croydon had to use extended hoses to reach the fire through the woodland.
Police were informed.
The Orchard Hill site is being developed currently as the site for the new Stanley Park High School.
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