At least 20 firefighters have been killed after responding to a huge fire in a commercial high rise building in Tehran, which caused the structure to collapse.

Iranian state media said it is believed people are still trapped beneath the rubble and that rescue efforts could go on for a further two days.

Soldiers, sniffer dogs and rescue workers were searching the ruins of the Plasco building after it crashed down in a giant cloud of dust. The collapse was shown live on state television and one witness described it as “like a horror movie”.

“At least 20 firefighters who were trapped under rubble have died,” Mayor Mohammad Baqer Qalibaf said. “They are martyrs. They lost their lives when trying to help people.”

But Tehran Fire Department spokesman Jalal Maleki told the broadcaster: “I cannot confirm the death of around 20 firefighters ... but some of them have been killed. The rescue operation continues.”

Dramatic footage showed the iconic structure collapsing in on itself in just a few seconds, taking out three fire trucks as it fell.

Thick plumes of brown smoke filled the sky and onlookers screamed as the building came down.

In pictures: Fire engulfs Iranian building and causes collapse Show all 12 1 /12 In pictures: Fire engulfs Iranian building and causes collapse In pictures: Fire engulfs Iranian building and causes collapse Firefighters battle a blaze that engulfed Iran's oldest high-rise, the 15-storey Plasco building in downtown Tehran Getty Images In pictures: Fire engulfs Iranian building and causes collapse Iranians watch the Plasco building engulfed by a fire, in central Tehran, Iran. The high-rise building engulfed by a fire collapsed on Thursday as scores of firefighters battled the blaze AP In pictures: Fire engulfs Iranian building and causes collapse Rescue workers gather in front of the collapsed iconic Plasco building in Tehran, Iran. Media reported that the major commercial building in Tehran has collapsed after hours of a severe fire, according to Iranian state media. At least 30 firefighters are believed to have died after being trapped on the upper floors of the building EPA In pictures: Fire engulfs Iranian building and causes collapse A firefighter reacts at the site of a blazing high-rise building in Tehran, Iran Reuters In pictures: Fire engulfs Iranian building and causes collapse Media reported that the major Plasco commercial building in Tehran has collapsed after hours of a severe fire, according to Iranian state media. At least 30 firefighters are believed to have died after being trapped on the upper floors of the building EPA In pictures: Fire engulfs Iranian building and causes collapse Firefighters try to put out a fire in a blazing high-rise building in Tehran, Iran Reuters In pictures: Fire engulfs Iranian building and causes collapse A firefighter breaks down at the site of a blazing high-rise building in Tehran, Iran. A number of firefighters are thought to have lost their lives attempting to tackle the blaze Reuters In pictures: Fire engulfs Iranian building and causes collapse Smoke rises from a blazing high-rise building in Tehran, Iran Reuters In pictures: Fire engulfs Iranian building and causes collapse An Iranian fire fighter cries as other prepare themselves. The iconic Plasco building collapsed after a fire in Tehran, Iran EPA In pictures: Fire engulfs Iranian building and causes collapse The building in Tehran collapsed after hours of a severe fire Reuters In pictures: Fire engulfs Iranian building and causes collapse Iranian fire fighters prepare as the iconic Plasco building collapses after a fire in Tehran, Iran EPA In pictures: Fire engulfs Iranian building and causes collapse Iranian fire fighters carry one of their injured colleagues in Tehran, Iran EPA

At least 88 people, including 45 firefighters were taken to hospital, state media had reported earlier. It did not specify whether those injured were hurt by the blaze or the building’s collapse.

The fire is now under control, fire department spokesperson Jalal Maleki said.

The 50-year-old Plasco, home to a major shopping centre, was one of Tehran’s most recognisable landmarks.

Dozens of anxious shopkeepers and others desperate to save their valuables were kept back by police as firefighters continued to secure the scene.

The tower was built in the early 1960s by Jewish businessman Habib Elghanian and named after his plastics manufacturing company.

At the time of its construction the Plasco was the tallest building on the city’s skyline.

The semi-official Tasnim news agency quoted an official in the Tehran governor’s office as saying an electrical short-circuit had caused the fire, but there was no immediate confirmation of this.

Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani sent condolences to the families of those killed. Mr Rouhani ordered an investigation and compensation for those affected, state TV reported.

Occupants of the building had been evacuated as firefighters tackled the blaze. State TV said the tenants included garment manufacturers, and it broadcast footage of business owners trying to re-enter the wreckage.

“I have lost everything. What am I going to do now. What should I tell my family?” owner of one of the 400 business units in the building, Mohsen Ghamisi, said.

Tasnim news agency reported that the business units and shops inside the building were not insured because of a lack of required safety measures.

Mr Maleki said: “We had repeatedly warned the building managers about the lack of safety.”

The owner of a nearby grocery store, forced by police to leave the area, said: “It was like a horror movie. The building collapsed in front of me.”

The semi-official Fars news agency said police had cordoned off the nearby British, German and Turkish embassies.