Two fires in Cambourne were started deliberately, firefighters have said.
Both were started in heaps of grass, including one on a rugby pitch, and Cambridgeshire Fire and Rescue Service is urging anyone with information about the cause of the blazes to contact police.
Crews from Papworth and Cambridge were called out to the first fire at 2.19am on Thursday and found around two tonnes of grass cuttings “well alight” on the rugby pitch in Back Lane.
They were at the scene for more than two hours.
A similar fire broke out in Broad Street at 1.17am on Friday involving half a tonne of grass which firefighters from Gamlingay put out with hoses.
Firefighters returned to the scene later in the morning to carry out an inspection.
They said both fires were believed to be deliberate and urged witnesses to contact police online at www.cambs.police.uk or to call Crimestoppers on 0800 555111.