UP to 20 firefighters tackled a blaze which spread through the basement of a multi-storey car park.
Crews attended the fire at the Civic Centre in Burdon Road, Sunderland city centre, on Monday night.
It is believed the blaze started in a rubbish compound of the four-storey building, igniting 40 plastic bins.
As crews from Sunderland central, Farringdon and Fulwell stations brought the fire under control, confining it to the basement, Metro train drivers were alerted to the possibility of smoke spreading to nearby lines.
A structural engineer was also brought in to assess damage to the roof of the basement and pipework.
A spokeswoman for Tyne and Wear Fire and Rescue Service said: “The fire was in a refuse bin compound, located on the basement level of a multi-storey car park.
“The basement was approximately 150 metres by 60 metres, where 40 large plastic refuse bins were severely damaged by fire.
“The basement level was severely damaged by fire, heat and smoke.
“A local authority structural engineer was requested to attend due to the heat damage to the concrete roof of the basement level and to assess a pipe which had become detached from its anchoring.
“Metro trains were also cautioned due to the amount of smoke issuing from the fire.”
Police were called to the scene, although it is understood there are no suspicious circumstances surrounding the incident.
A spokeswomen for Northumbria Police said: “At 9.40pm, police received a call from the fire service about a fire at the Civic Centre multi-storey car park.
“Officers attended the scene where the fire happened in the secure basement of the building.
“The fire was brought under control by 10.22pm.”