Bangor High Street has been closed while firefighters deals with a "significant" fire above a restaurant.
Three appliances first attended Noodle One after receiving a call at 2.55am on Tuesday. An aerial ladder was also in use.
The road was closed been between the Cathedral and The Varsity Pub.
North Wales Fire and Rescue Service confirmed the fire has been extinguished. Structural engineers are now assessing the safety of the building.
North Wales Police said it cannot confirmed how long the closure will be in place for.
North Wales Fire and Rescue Service station manager Aaron Spencer said: “We attended an incident at Noodle One bar in Bangor High Street.
"Three fire engines, one from Menai Bridge and two from Bangor, along with an aerial ladder appliance from Bangor also attended.
"We have had a significant fire within the building, which has now been extinguished successfully by the crews that attended."
He also thanked the member of the public who called the fire service to inform them of the fire.
"It is currently being made safe so that we can continue our fire investigation into the cause of this incident.”