Police are investigating two separate arson attacks in which 15 vehicles were damaged.
The first incident happened in the Old Saintfield Road area of Carryduff on Wednesday night.
Police received a report that shortly after 10pm eight cars and a lorry that were parked at a property in the area, and in the street nearby, had been targeted.
Several of the vehicles were completely burnt out, with others partially damaged, officers said.
The PSNI said it was working to establish a motive for the attack and appealed to anyone with information, or dashcam footage from the area, to come forward.
The second arson incident happened at a commercial premises in the Diamond Gardens area of Finaghy in south Belfast in the early hours of Thursday.
Officers received a report that at around 1am an accelerant had been poured over the fence of a garage yard in the area and set alight.
This caused damage to six cars inside the yard and the fence at the property.
Officers have appealed for anyone who noticed suspicious activity in the area or who has information about the incident to come forward.
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