Some five derelict caravans were set alight in the village of Dunston near Lincoln overnight on May 5.
Police and Lincolnshire Fire and Rescue attended the large fire at around 6.20pm. On their arrival they found a number of what are described as derelict caravans, with five of them alight.
An investigation into the cause of the fire is underway, and officers are treating the incident as suspected arson.
Police are asking for anyone who may have any information that will help their enquiries to contact them on the non-emergency number 101 quoting incident 365 of May 5.
Alternatively, people can contact the independent charity Crimestoppers anonymously on 0800 555 111.