Police are combing through CCTV as they work to determine who set three Teslas alight at a dealership in Sydney's west, damaging the rest of the showroom.The fire was originally thought to have started due to a battery explosion, but it was quickly ruled an arson attack after jerrycan lids were discovered near the Parramatta dealership.Three cars were destroyed, and a showroom was badly damaged, but there were no injuries.LIVE UPDATES: Trump threatens to wipe out critical island, UN calls