Early on Tuesday morning, a BMW and a delivery vehicle were set on fire at Glostrup Storcenter, a shopping centre roughly ten kilometres west of downtown Copenhagen.
Unlike the car fires of the previous two nights, police said that there was no doubt about the cause.
“We presume that the fire was set and we'd like to hear from witnesses who may have seen or heard something. There is an ongoing investigation and we don't have any additional comments,” Copenhagen Vestegn Police spokesman Brian Munck told news agency Ritzau.
The Glostrup car fires followed two similar incidents over the weekend. In the first, a total of eight cars were found burnt at a vehicle safety testing centre in the suburb of Brøndby. The following night, eight more cars were burnt in a residential carport in Albertslund.
A 21-year-old Amager man has been arrested on the suspicion that he was behind at least some of the incidents but around half of the total vehicle fires have happened after the man's arrest.
Police have been cautious about drawing direct parallels to a similar spate of car fires in Sweden.