Pir Hossein Kulivand, an Iranian emergency official, later told state TV all those on board were killed in the crash. He said rescuers were trying to collect the dead. "The plane is on fire but we have sent crews ... and we may be able to save some passengers," he said on television.

State TV earlier said there were 180 passengers and crew aboard. The discrepancy could not be immediately reconciled.

Flight data from the airport showed a Ukrainian 737-800 flown by Ukraine International Airlines took off Wednesday morning, then stopped sending data almost immediately afterward, according to website FlightRadar24. The airline did not immediately respond to a request for comment.

Associated Press journalists who reached the crash site saw a wide field of debris scattered across farmland. The dead lay among shattered pieces of the aircraft. Rescuers in masks shouted over the noise of hovering helicopters as they worked.

The crash came hours after Iran launched a ballistic missile attack targeting two bases in Iraq housing US forces in retaliation for the killing of Revolutionary Guard General Qassem Soleimani.

The Boeing 737-800 is a very common single-aisle, twin-engine jetliner used for short to medium-range flights. Thousands of the planes are used by airlines around the world.

Introduced in the late 1990s, it is an older model than the Boeing 737 MAX, which has been grounded for nearly 10 months following two deadly crashes.

Several 737-800 aircraft have been involved in deadly accidents over the years.

In March 2016, a Flydubai 737-800 from Dubai crashed while trying to land at Rostov-on-Don airport in Russia, killing 62 on board. Another 737-800 flight from Dubai, operated by Air India Express, crashed in May 2010 while trying to land in Mangalore, India, killing more than 150 on board.

Chicago-based Boeing did not immediately respond to a request for comment. Boeing, like other airline manufacturers, typically assists in crash investigations. However, that effort in this case could be affected by the US sanctions campaign in place on Iran since President Donald Trump unilaterally withdrew from Tehran's nuclear deal with world powers in May 2018.

Both Airbus and Boeing had been in line to sell billions of dollars of aircraft to Iran over the deal, which saw Tehran limit its enrichment of uranium in exchange for the lifting of economic sanctions. But Trump's decision halted the sales.

Under decades of international sanctions, Iran's commercial passenger aircraft fleet has aged, with air accidents occurring regularly for domestic carriers in recent years, resulting in hundreds of casualties.

AP with Reuters