A huge fire engulfed council offices in Oxfordshire during a spate of suspected arson attacks involving gas canisters that badly damaged two other buildings.
A man has been arrested over the three blazes, which also damaged a funeral parlour and a thatched cottage.
A car ploughed into South Oxfordshire District Council's building in Crowmarsh Gifford, causing huge damage.
Gas canisters were found at all three fire sites as well as the home of the 47-year-old suspect in Roke.
Police said links between the three fires at the council building, the nearby funeral parlour and the cottage in Rokemarsh, were under investigation.
Supt Andy Boyd said: "We are searching another address at Roke at the moment, there are gas canisters in that premises."
South Oxfordshire District Council leader John Cotton said the planning department "has pretty much disappeared".
"It's going to be very hard to provide any services that that are provided directly from here," he said.
"Happily that isn't too many in the short term."
The council office fire is under control but firefighters expect to be on the scene for a "significant period of time".
Oxfordshire's chief fire officer Dave Etheridge told the BBC: "We believe there were gas canisters used in all of the locations at the moment.
"We have the ability to call upon our colleagues in bomb disposal just to make sure that the scene is maintained in terms of a safe area."
He said it had been a "challenging night" for the 150-strong fire crew called to the three locations.
Eyewitness Karl Mitchell-Shead told the BBC he saw a burnt-out vehicle in the foyer of the council building.
"We wondered if someone had accidentally driven into it, or purposely driven into the foyer, but certainly it looks like that's where the fire started.
"That was the area that was most heavily damaged."
Alastair Cox, owner of the funeral parlour, said: "They've put a big gas canister through our front door, set fire to it.
"Dad saw the car leave our place, go round to the council offices and it looks like they have done exactly the same there."
The fire service was called shortly after 03:10 to the fire at the thatched cottage and derelict buildings on Quakers Corner in Roke Marsh, near Benson, and to the funeral parlour in Benson Lane, Crowmarsh Gifford, at 03:20.
Thames Valley Police said the investigation was focusing on all three fires being linked and suspicious.
Nobody was hurt during the fires and the buildings are being examined, police said.
The local man, 47, was arrested on suspicion of arson and is in custody.
'Bangs and pops'
About 400 staff from departments including housing, planning, building control and leisure work at the council building on Benson Lane.
The headquarters is also home to about two-thirds of the Vale of the White Horse District Council's staff.
Andy Roberts, senior communications officer for the councils, said most services would be affected.
Andrea Turner, who can see the offices from her bedroom window, described the fire as "really bad".
"I could hear loads of bangs and pops and got up to see what it was and saw massive high flames coming from the top floor of the building.
"The roof is now caved in and everything. It's all gone."
Ian Negus saw the early stages of the fire.
"I saw 60ft flames when I heard a bang outside.
"Half of the building was relatively sound, but the other half was completely exposed, and, with the wind, over the next couple of hours it got engulfed with flames.
"It was quite alarming how quickly it spread."
The council was trying to reduce the impact of the fire on front-line services and will set up an emergency phone line for people who have urgent inquiries.
Other councils have offered assistance to the two authorities affected by the fire. Oxfordshire County Council, Oxford City Council and Henley Town Council are all offering office space to staff.
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