TEHRAN, Jan. 19 (Xinhua) -- Tehran's mayor confirmed the death of 20 fire fighters in the commercial building in the capital of Iran on Thursday, Tasnim news agency reported.

Earlier reports said at least 30 people were killed in the collapse of a 17-story commercial building.

Mohammad Baqer Qalibaf said that unfortunately the building with 600 commercial shops caught fire on Thursday morning and the firefighters were actively engaged in the rescue operations.

Twenty of the trapped firefighters in the building were killed, Qalibaf said.

At 8:00 a.m. local time (0430 GMT), the fire started from the eighth and ninth floors of the building located on Jomhouri Eslami street, in the downtown area of the capital, and soon it was spread to the upper floors.

The 54-year-old building was very fragile and ravaged by fire despite firefighters' efforts.

Local media also reported that some 70 people were also injured in the incident.

The residents of buildings in the neighborhood have been warned by the police and the rescue operators to leave the buildings.

Also, nearby buildings including the embassies of Turkey and the UK have been evacuated. Authorities at Tehran's governor's office have ruled out terrorism, Press TV said.