Two more cars have been set on fire in Birchwood in Lincoln over the weekend, the third and fourth similar incidents in the area this month.
Both fires were reported in the early hours of Saturday, May 17.
At around 12.30am, police received a call reporting a green Volkswagen Polo car on fire at Halton Close in Lincoln.
The caller had managed to notice the fire at an early stage and extinguished it.
Another report was made to Lincolnshire Police just after 4am, of a Vauxhall Vivaro van on fire at Sycamore Crescent in Lincoln.
Officers say the fires are believed to have been started deliberately, and enquiries are being made as to whether they are related to two other vehicle fires earlier this month.
03:54-Crew from Lincoln South attended a van fire on Sycamore Crescent, Lincoln.Fire extinguished 1 hosereel and cutting gear for access.
— Lincs Fire & Rescue (@LincsFireRescue) May 17, 2014
As previously reported, a blue Mini Cooper was set on fire on Fulmar Road in Birchwood on May 5.
On May 14, three cars were damaged by a blaze on Nightingale Crescent in Birchwood.
Officers are still investigating the fire which totally destroyed a grey Volkswagen Touran.
There have been no injuries at any of the reported incidents.
Residents in the Birchwood area have also recently alerted police to a number of vandalism and graffiti incidents.
Some eight cars were spray painted and outbuildings written on with black paint overnight between April 24 and 25.
Officers are appealing to anyone who witnessed anything suspicious around the areas of Halton Close and Sycamore Crescent on May 17 to get in touch.
Anyone with any information is asked to contact Lincolnshire Police on 101 quoting incidents 15 and 86 of May 17,2014.
Alternatively, you can contact the independent charity Crimestoppers anonymously on 0800 555 111.