A bomb disposal team is examining the wreckage of a car inside the fire-damaged offices of South Oxfordshire District Council.
Police believe a vehicle crashed into the building before it burst into flames.
Firefighters are continuing to investigate a major fire at a council office building in South Oxfordshire.
Police believe the building, as well as a thatched house and a funeral home, were deliberately targeted and officers have arrested a 47-year-old man on suspicion of arson.
ITV News Correspondent Dan Rivers is at the scene:
Fire crews in Oxfordshire have been dealing with three fires. They were called to a thatched cottage at Rokemarsh, a nearby funeral parlour and the buildings of South Oxfordshire District Council. Video shows damage to the cottage. A man has been arrested on suspicion of arson.
ITV News Correspondent Dan Rivers tweeted:
Latest aerial video from Oxfordshire shows the aftermath of the fire at the local council offices.
Eyewitness Karl Mitchell-Shead has told ITV News that he saw the wreckage of a car inside the South Oxfordshire District Council office building.
"There was what looked like a chassis of a vehicle - I'm pretty sure someone had driven into the foyer," Mr Mitchell-Shead said.
The amateur photographer said the building had been "completed devastated" by the blaze.
A vehicle may have "collided" with the South Oxfordshire District Council building before a huge fire, police have said.
- Police believe three fires at a council office, a thatched house and a funeral home in Oxfordshire are linked
- The first fire at a thatched property was reported at 3.11am
- The second at a funeral home was at 3.20am
- A fire at council office buildings was reported at the same time
- A 47-year-old has been arrested on suspicion of arson
- Police believe a vehicle may have "collided" with building prior to fire
- No injuries have been reported
- It is not believed to be a terrorist act
Thames Valley Police have advised that there are no reported injuries as a result of today's fires in Oxford.
A 47-year-old man has been arrested on suspicion of arson following three fires in Oxfordshire, including at a council office building.
The suspect is currently in custody.
Thames Valley Police said the fires are not believed to be linked to terrorism.