At least 20 firefighters were killed when a high-rise building in Tehran caught fire and collapsed, the mayor of the Iranian capital has said.
Two hundred had battled the blaze in the landmark 17-storey Plasco building for several hours before it fell to the ground in a matter of seconds.
Another 70 people were injured, 23 of them seriously, in the incident.
Completed in 1962, the building was once Tehran's tallest and contained a shopping centre and clothing workshops.
The cause of the fire is not known, but several officials said managers had been warned about safety issues.
The fire reportedly began on the ninth floor at around 08:00 (04:30 GMT).
Initial photos showed flames and smoke pouring out of the top of the building.
Ten fire stations responded to the blaze and state television reported that dozens of firefighters were inside the building when the north wall collapsed, swiftly bringing down the whole structure.
One of the firefighters told AFP news agency: "I was inside and suddenly I felt the building was shaking and was about to collapse. We gathered colleagues and got out, and a minute later the building collapsed."
"It was like a horror movie," the owner of a nearby grocery shop told Reuters.
Rescue workers and sniffer dogs searched the rubble for several hours before Tehran Mayor Mohammad Baqer Qalibaf announced that 20 firefighters had died.
Earlier, he said that "no ordinary civilians" were believed to be missing, but witnesses told the Associated Press that they had seen some people slip through the police cordon in an attempt to retrieve their possessions.
Some business owners were later filmed by state TV trying to enter the ruins.
Masoumeh Kazemi said her two sons and a brother had jobs at one of the many clothing workshops inside the building.
"I do not know where they are now," she told the Associated Press in tears.
Police officers have cordoned off Jomhoori avenue, which passes by the building, as well as the nearby British and Turkish embassies.
Fire department spokesman Jalal Maleki said it had repeatedly told the building's managers that it was unsafe, and that it had lacked fire extinguishers.
"Unfortunately, there were loads of goods inside the building and its staircases and none of the safety measures had been observed." he told the Isna news agency.
The Tasnim news agency reported that the building "had caught fire in the past".
President Hassan Rouhani ordered Interior Minister Abdolreza Rahmani-Fazli to investigate the incident, calling it "extremely sad and unfortunate".
The Plasco building was built by the Iranian Jewish businessman Habib Elghanian and was named after his company, which manufactured plastics. He was executed after the 1979 Islamic Revolution after being convicted of spying for Israel.