Arsonists are thought to have torched an empty building near Wisbech park.
Emergency services were called at 3.10pm on Sunday (25) to the incident in William Road on the edge of Park Road.
Cambridgeshire Fire and Rescue Service and local police attended the incident.
The building was last used to house newspapers and post by Brian Webb Postal Service.
A Cambridgeshire Police spokesman said: “An outbuilding was on fire and it was believed to have been started deliberately.
“Scenes of crime officers have attended the area and an investigation into the incident is ongoing.”
A spokesman for Cambridgshire Fire and Rescue said: “On Sunday at 12.17pm, one crew from Wisbech and one crew from March were called to a house fire on William Road, Wisbech.
“Firefighters arrived to find a fire in a garage attached to a house.
“Wearing breathing apparatus and using one hose reel, firefighters extinguished the fire, before returning to their station by 2.40pm.
“The cause of the fire was deliberate.”
Anyone with information regarding this incident should call police on 101 quoting CF0158770318 or visit www.cambs.police.uk/report. Alternatively, contact Crimestoppers, anonymously, on 0800 555111.
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