Firefighters have been tackling a fire at the telephone exchange in Alnwick town centre.
The flames erupted in the exhaust of the stand-by generator at the site. The incident was caused by birds nesting against the hot exhaust.
Three appliances – two from Alnwick and one from Amble – were called to the scene, behind Fenkle Street, after receiving the call at 11.35am.
The blaze, described as accidental by a Northumberland Fire and Rescue Service spokeswoman, is now out.