A fire which has caused the Skipton Building Society in Market Square to close is believed to have been caused by overheating cables.
A Skipton spokeswoman said: “The fire appears to have started in a cupboard that houses communications cables.
“It looks like the cables overheated and started a fire.”
The blaze spread to the first floor kitchen and staff room area of the building.
The first floor of the building was 50% damaged by fire, with other floors suffering smoke and water damage.
No one was injured in the incident, with staff quickly evacuated.
Staff from the branch have been relocated to Oxford and Chesham for now, with customers able to use those sites or the company’s call centre while the Aylesbury unit remains closed.
It is not yet known when it will re-open.
A Skipton spokeswoman said: “The fire was quickly extinguished and nobody was hurt.
“We have temporarily closed the branch while the fire service pinpoints the cause.
“We will let customers know as soon as possible when the branch will be re-opening.”
There will be a member of staff at the site on Wednesday to let customers know what is going on.
Three fire crews rushed to the scene at 3.09pm on Tuesday and used two hose reels to put out the blaze.