A military transport plane has crashed on the outskirts of the Iranian capital Tehran, killing at least 128 people.
The plane was attempting an emergency landing at Mehrabad airport and came down in a residential district, hitting a 10-storey apartment building.
The impact set off a big explosion, setting fire to the building.
Iranian state-run radio said all 94 passengers and crew on board the C-130 plane, and 34 people on the ground, were killed.
The aircraft had just taken off when the pilot reported an emergency and turned back, before losing control of the aircraft.
The fuel tanks were almost full so there was a large blast on impact with the base of an apartment block in a compound housing airport staff in the Yaftabad district.
"I saw the aeroplane. There was smoke coming out of one engine. It went into the ground very fast, very close to the building," said 30-year-old Mohammad Rasooli, a local resident.
"There was a huge explosion which engulfed the housing block."
Most of the passengers on board the plane were journalists and photographers from Iranian news agencies on their way to cover military manoeuvres on the southern coast. Nearly 40 employees of state-run television died.
The building remained standing but is a scorched shell.
Officials said several children, at home because schools were closed because of a smog alert in the capital, were among those who died in the apartment block.
"Most of the victims on the ground are women and children who were at home," Lieutenant Nasser Sedigh-Nia, who witnessed the crash, told AFP news agency.
An interior ministry spokesman said some of those killed on the ground had been in their cars, whose burnt-out shells littered the crash site.
Scores of people were taken to hospitals suffering from burns and the effects of smoke.
Scuffles broke out as police cordoned off the crash site, trying to keep hundreds of anxious residents from pushing past them.
And journalists at the site were beaten and had their tapes confiscated by the security forces.
The BBC's Frances Harrison in Tehran says the Iranian army has denied rumours that the flight crew was aware there were technical problems with the plane.
IRAN'S AIR DISASTERS
Feb 04: Iranian plane crashes near Sharjah airport in UAE, killing 43 people
Feb 03: Military transport aircraft crashes in southern Iran, killing 302 people
Dec 02: Commuter plane carrying aerospace experts crashes in Iran, killing 46 people
Feb 02: Tu-154 operated by Iran Air crashes in mountains in west of Iran, killing 117 people
March 97: 80 die when a military plane crashes in north-east Iran
Feb 93: Tu-154 crashes into a military plane near Tehran, killing 132
It was said to have nearly crashed a week ago, and its engines had to be switched on and off five times before it could take off on its final flight.
In a message carried by state media, Iranian President Mahmoud Ahmadinejad said: "I learned of the catastrophe and the fact that members of the press have been martyred.
"I offer my condolences to the supreme leader and to the families of the victims".
The Iranian air force is believed to have about 15 ageing US-made C-130s in operation, dating back to before the 1979 Islamic revolution and the US boycott of Iran.
The country's civil and military aircraft have a poor safety record.
In 2003, an Iranian Ilyushin-76 troop carrier crashed in south-east Iran killing all 276 Revolutionary Guard soldiers and crew aboard.
Officials blame the high frequency of crashes on a lack of aviation spare parts due to US sanctions.
Mehrabad is the oldest airport in Tehran and handles both domestic and military flights.
When it was built more than 60 years ago it was located outside the capital, but with the growth of Tehran's urban sprawl the airport has become surrounded by residential areas.
Heavy-lift transport aircraft built by Lockheed Martin, known as the Hercules in the UK
Iran has some 15 C-130 E and H types dating from the mid-1970s
A modern US variant is the AC-130 - a heavily armed gunship version - used in Iraq and Afghanistan
First flew: 1956
Max. take off weight: 69,750kg
Engines: 4 Allison turboprops
Range: 2,356 miles