Firefighters tackled a two-car blaze in Haverhill after a suspect was seen setting one alight by a member of the public.
Suffolk police said it received a call at 7.24pm regarding a suspicious male in dark clothing reportedly setting light to a car in Gloucester Road in the town.
A house near the vehicles was also evacuated as a precaution, according to a spokeswoman for Suffolk police.
Firefighters extinguished the cars in around 30 minutes but both cars were completely destroyed.
Investigations into the blaze are taking place.
Police are appealing to witnesses or anyone who saw anything suspicious to come forward. Call police on 101 or Crimestoppers, anonymously, on 0800 555111.
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