Lincolnshire Fire and Rescue say they were called in at 2.19am to a fire at The Drove in Sleaford as residents were awoken by the smell of smoke and noise from the flames.
Two derelict wooden agricultural buildings were alight and two fire crews attended from Sleaford, along with support of crews from Grantham, Billinghay and Metheringham, and the water carrier from Holbeach.
They took at least three hours to put it out using three main jets, eventually leaving the scene at 8.19am.
No-one was reported to have been hurt but the cause has been established as arson and will be investigated by the police. Anyone with information is asked to contact 101 quoting incident number 277 of April 14.
The remains continued to smoulder through the morning and crews revisited to inspect it later in the day and were carrying out another re-inspection later today (Thursday).
One resident said on Facebook that she awoke thinking she heard fireworks and looked out and thought she could see fire.
“It was a shame something like this happened but pleased no one hurt.”
Another resident said: “Never heard anything until about 2.10am. It was a right old blaze then.”
Another added: “It was still smouldering at lunch time yesterday (Wednesday) and there was lots of ash on stuff in our garden. I could still smell it when I went to bed last night but seems to have cleared this morning. Glad no one was hurt.”