A passenger plane has skidded off a runway and burst into flames in Iran's north-eastern city of Mashhad, killing 29 of those aboard.
Early reports said a tyre had burst
Early Iranian TV reports had put the death toll at 80 for the Russian-built jet carrying at least 148 people from the southern port city of Bandar Abbas.
The fire began when the Tu-154 left the runway on landing at 1345 (1015 GMT), possibly because of a burst tyre.
Mashhad is a popular destination for Shia pilgrims visiting a shrine there.
Television pictures showed a broken, partially charred plane lying on the side of a runway, as firefighters damped down the smouldering wreck.
Nourollah Rezai Niaraki, chairman of Iran's Civil Aviation Organisation, said in an interview on TV that the plane had slid off the runway, "then its left wing hit the ground and caught fire".
Much of the plane's fuselage was charred
He said that 29 people had died, correcting the earlier TV reports.
Speaking from his hospital bed, a passenger who survived the crash described the landing on Iranian TV:
"The plane was going up and down when we were trying to land.
"When we landed, I heard a huge sound from underneath the plane.
"The plane leaned to one side and started sliding on the ground and then a fire started from the front of the plane."
A spokesman for the Civil Aviation Organisation, Reza Jafarzadeh, said the cause of the incident was still not clear.
But the flight's crew survived the accident, Roads and Transport Minister Mohammad Rahmati told Iran's student news agency Isna.
"This will be a great help to find out the cause of the accident as soon as possible," he added.
Air disaster history
The BBC's Tehran correspondent, Frances Harrison, says Mashhad, which lies 1,000 km (620 miles) north-east of the capital, is a major pilgrimage destination for devout Shias as it houses the shrine of Imam Reza.
Iran has had a bad record in airline safety, our correspondent says.
Planes from Iran Air Tours crashed in 2002 and 1993 - on both occasions, there were no survivors.
The Tupolev-154 has for more than a quarter of a century been the backbone of Russian and Soviet air transport.