IRNA Tehran's Fire Department spokesman announced on Wednesday that the blaze in a multi-storey building owned by the Ministry of Energy was contained after some 48 hours of relentless efforts.
Jalal Maleki told the Islamic Republic News Agency (IRNA) that there was no apparent flame in the building, and the firefighters launched the smoke ventilation and the complimentary operation.
Extinguishing the fire is the main phase of operation that was accomplished as the result of firefighters' efforts, he said.
The building of thermal electricity office in downtown Vali-e Asr square, Tehran, has been burning since Monday morning.
The fire began from the floor minus four on Monday morning and spread to other floors rapidly.
The tempreture of the building that rose to 400 degrees centigrade on Monday, fell to 250 degrees centigrade on Tuesday.
The spokesman also expressed hope that the rest of the operation goes with no collapse, as it is not ruled out yet.
The Public Relations Department of Tehran emergency services, 16 firefighters were injured in the operation.
In January 2017, another blaze caused the renowned 17-story building, Plasco, collapse in downtown Tehran. It left 20 firefighters dead and some 70 injured.