Police have launched an arson investigation after tents used by homeless people were set alight, including one with a man inside it.
Fire crews were called to Grantham's South Lodge Park – known locally as The Paddocks – at about 01:50 BST.
The occupant – a man in his 40s – suffered no serious injuries, Lincolnshire Police said.
The force said it was treating the incident as arson with intent to endanger life.
One tent was destroyed in the blaze while another two were badly damaged.
"The area is sheltered by trees, and we know that the time of morning [when] this happened will mean [the number of] witnesses is limited," a police spokesperson said.
The force is asking people to check CCTV, doorbell cameras and dashcam footage on surrounding roads and paths to see if it captured anyone in the area at the time.
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