Tehran - Rescue workers in Tehran were desperately hunting for firefighters trapped under the rubble after a fire Thursday led to the collapse of Iran's oldest high-rise, the 15-storey Plasco building.Officials had yet to confirm if anyone had been killed, but Tehran mayor Mohammad Bagher Ghalibaf told state television that between 20 and 25 firefighters were thought to be inside when the building fell. Three people were pulled alive from the rubble and taken to hospital, the head of Tehran's emergency services said, according to the ISNA news agency. At least 70 firefighters were injured and 23 hospitalised as they rushed to evacuate the building, which had been on fire for around four hours before it crumbled, the head of emergency services told state television.Around 200 firefighters had been tackling the blaze at the Plasco building, which dated from the 1960s and included a shopping centre and clothing workshops.Dramatic images showed flames pouring out of the top floors just before it came down live on television."I was inside and suddenly I felt the building is shaking and is about to collapse. As we gathered colleagues and got out, a minute later the building collapsed," said Ali, a firefighter at the scene.Local media said the workshops were especially full of clothes in the build-up to Nowruz, the Iranian new year, which falls in March. President Hassan Rouhani called for an immediate investigation into the causes of the incident, calling it "unfortunate and sorrowful". "More than 30 times we warned the building's owners that it was not safe, but unfortunately they did not pay attention," said Shahram Gilabadi, spokesperson for the municipality.Fire brigade spokesperson Jalal Malekias said the building was known to breach safety standards."Even in the stairwells, a lot of clothing is stored and this is against safety standards. The managers didn't pay attention to the warnings," he told state television, adding that it lacked sufficient fire extinguishers.'Thousands ruined' The steel skeleton of the building could be seen bending down to the ground as around 100 fire engines and dozens of ambulances surrounded the area.Smoke was still pouring from the street hours later. Firefighters caked in soot wept outside the building as the hunt for their colleagues continued, and local media showed Tehranis queuing to donate blood. "I've lost my entire stock. Thousands of families have been ruined," said Ahmad, the owner of one of the 400 shops and business units. The Plasco building was the first high-rise and shopping centre in Tehran and was the city's tallest building when it was finished in 1962, before being dwarfed by the construction boom of later years. It was built by Habibollah Elghanian, a prominent Iranian-Jewish businessman who was arrested for ties to Israel and sentenced to death and executed after the 1979 Islamic revolution. The fire is thought to have begun on the ninth floor and spread quickly to workshops above.Iranian firefighters work to extinguish fire of the Plasco building in central Tehran, Iran. (Vahid Salemi, AP) Firefighters were initially able to bring it under control but it quickly flared up and the building fell four hours after the fire had started, at around 11:30 (08:00 GMT).A crisis meeting was held at the scene with Tehran's governor, police chiefs and officials from the Red Crescent. The army was also deployed to assist with the rescue effort."There were a number of people inside but we don't know how many and the fire brigade organisation is going to announce how many were there," Tehran police chief Hossein Sajedinia told AFP."Even one would be too many," he added.