A Ukrainian Boeing 737-800 carrying 176 people on Wednesday crashed shortly after takeoff from Tehran, killing everyone on board.
The circumstances of the crash are not fully known. The Iranian state news media cited technical problems on the plane, which was bound for Kyiv, Ukraine’s capital.
The disaster happened against the backdrop of the escalating tensions between the United States and Iran, which on Tuesday attacked two bases in Iraq that house American troops. It also has the potential to add to the crisis at Boeing, which has been dealing with the fallout from two crashes involving a different jet.
Photos and videos from the crash site showed rescuers in a field littered with plane debris, smoldering fires and the personal belongings of passengers. The Iranian Students’ News Agency, a state-run media organization, shared a video it said showed the predawn crash, with a distant light descending in the distance before a bright burst filled the sky upon impact.
Qassem Biniaz, an official at the Iranian Ministry of Roads and Urban Development, told the Islamic Republic News Agency, the government’s official news agency, that an engine caught fire and the pilot was unable to regain control. Ukraine International Airlines Flight 752 left Imam Khomeini International Airport in Tehran at 6:12 a.m. on Wednesday and lost contact at 6:14 a.m., according to a flight tracker.
After the crash, Ukraine’s Embassy in Iran initially issued a statement ruling out terrorism or a rocket attack as a cause of the crash. But the statement was later removed from the embassy’s website and replaced by a statement saying it was too early to draw any conclusions about what had happened.
At a news conference at Kyiv’s Boryspil International Airport several hours after the crash, Ukraine International Airlines executives said the plane was in good working order and operated by highly trained crew. They offered no theories as to what might have happened and declined to comment on whether or not it might have been shot down.
“Given their experience, it is very difficult to say that there was something wrong with the crew,” Ihor Sosnovskyi, the airline’s vice president of flight operations, said at the briefing.
President Volodymyr Zelensky of Ukraine said he had ordered the prosecutor general to open a criminal investigation into the crash and that the country’s entire civil aviation fleet would be checked.
“All possible versions of what occurred must be examined,” Mr. Zelensky said in a Facebook post.
Boeing faces its own pressure. The company has been under intense scrutiny after the crash of two 737 Max jets in less than five months, which together killed 346 people. The Max has been grounded worldwide since March, creating a crisis for the company and leading to the firing of the chief executive.
As the company struggles to get a fix for the Max approved by regulators, new safety risks have recently emerged with the plane, which the company may also need to assess on the 737 NG. The Boeing 737-800 is part of the 737-NG family.
“We are aware of the media reports out of Iran and we are gathering more information,” Boeing said in a statement.
The crash came at a tense time in Iran, as conflict with the United States had the country on edge. On Tuesday, the F.A.A. barred American airliners from flying over Iran, citing the risk of commercial planes being mistaken for military aircraft. Several non-American carriers rerouted their flights on Wednesday to avoid Iraq and Iran, according to Flightradar24, a site that tracks airplane transponders.
The airline said 167 passengers and nine crew members were on board.
Vadym Prystaiko, Ukraine’s minister of foreign affairs, said the victims included 82 Iranians and 11 Ukrainians, including nine Ukrainian crew members. Sixty-three passengers were from Canada, 10 from Sweden, four from Afghanistan, three from Germany and three from Britain, he said.
The crash could touch a nerve politically in Ukraine, as Ukraine International Airlines is partly owned through a network of offshore companies by Ihor Kolomoisky. Mr. Kolomoisky is an oligarch with close ties to the Ukrainian president.
Mr. Zelensky cut short his trip to Oman, where he was spending the holidays, and was returning to Kyiv. “Horrible news from the Middle East,” he said in a post on Facebook. “My sincere condolences to the relatives and loved ones of all of the passengers and crew members.”
While airlines in the former Soviet Union have a generally poor safety record, Ukraine International Airlines says on its website that its safety is audited and meets Federal Aviation Administration standards for code-sharing flights with foreign partners. It had not previously suffered a fatal crash, according to a list of Ukrainian aircraft accidents compiled by the Flight Safety Foundation.
The airline said the plane was manufactured in 2016 and delivered directly from the factory, and that it had most recently undergone scheduled maintenance on Monday — two days before the crash. The airline said it was canceling flights to Tehran indefinitely and promised a full investigation into the causes of the crash, involving officials from Ukraine, Iran and Boeing.
The airline began in the 1990s as newly independent Ukraine’s state flag carrier but was subsequently privatized. Its website calls the business a “public private entity.” Before suspending service to Tehran on Wednesday, the carrier offered five direct flights per week from the Iranian capital to Kyiv. The airline flies a fleet of 35 Boeings and seven Embraer aircraft, according to its website.
Officials from the Ukrainian Embassy in Tehran were at the airport Wednesday morning and working to compile a list of the passengers on board, Russia’s state-run RIA Novosti news agency cited an embassy official as saying. Ukraine’s Foreign Ministry said it had set up a crisis working group and a telephone hotline in response to the crash.
Daniel Victor reported from Hong Kong, and Anton Troianovski and Andrew Kramer from Moscow. Farnaz Fassihi contributed reporting from New York.