US officials believe that Ukraine International Airlines Flight 752 was likely shot down by an Iranian surface-to-air missile, according to multiple reports on Thursday.

US officials told The Associated Press that it was "highly likely" that Iran was responsible.

Defense officials told Newsweek and others that the plane was probably shot down by accident, as Iran's surface-to-air missile systems were likely active at the time of the crash early Wednesday.

The plane went down shortly after Iran fired a barrage of ballistic missiles at US and coalition forces in Iraq in response to a US drone strike that killed Maj. Gen. Qassem Soleimani last week.

Visit Business Insider's homepage for more stories.

US officials believe Ukraine International Airlines Flight 752 was hit by fire from a Soviet-built surface-to-air missile system operated by Iranian forces, according to multiple reports.

The plane crashed outside the Iranian capital of Tehran early Wednesday, killing all 176 people on board, shortly after Iranian forces launched a barrage of missiles at US and coalition forces in Iraq in response to a US drone strike that killed a top Iranian general — Maj. Gen. Qassem Soleimani, former head of the IRGC Quds Force.

US officials told Newsweek, Reuters, and other outlets that the incident was likely an accident, as anti-aircraft systems were likely active at the time of the crash.

The Pentagon declined to comment on the reports.

CBS News reported that US officials were confident that Iran shot down Flight 752.

Sources told the outlet that US intelligence detected anti-aircraft radars turning on before the crash and that satellites detected two infrared blips, thought to be SA-15 missiles, that were quickly followed by another blip, the suspected aircraft explosion.

CNN confirmed CBS and Newsweek's reporting, and US officials told The Associated Press that it was "highly likely" that the aircraft was downed by an Iranian anti-aircraft missile.

The downed aircraft was made by Boeing, which saw its stock surge as much as 3% on Thursday on the news that it might have been struck by an Iranian missile. There had previously been speculation that a technical issue caused the crash.

President Donald Trump said on Thursday that he did not believe that the passenger jet went down as a result of a mechanical error, according to CNBC.

"It was flying in a pretty rough neighborhood," the president said. "Someone could have made a mistake." Trump added: "I have a feeling that — it's just some very terrible, something very terrible happened, very devastating."

Citing a US official, ABC News reported that US intelligence was confident that Iran "painted the Ukrainian airliner with radar and fired two surface-to-air missiles that brought down the aircraft."

Canadian Prime Minister Justin Trudeau said on Thursday afternoon that Canada also had intelligence and evidence from multiple sources indicating "that the plane was shot down by an Iranian surface-to-air missile."

He added that "this may well have been unintentional" and expressed a desire for a full investigation.

Oleksiy Danylov, the secretary of Ukraine's National Security and Defense Council, wrote on Facebook earlier Thursday that Ukrainian investigators were considering several possibilities, including the plane being shot down, an engine explosion due to a technical malfunction, a terrorist attack on the flight, or even a collision with an unmanned aerial vehicle.

Images appearing to show Tor missile fragments, said to have been found outside Tehran, have been circulating on social media. A video making the rounds appears to show the moment a missile struck the Ukrainian aircraft.

Iran has denied responsibility, with Iranian media, citing state officials, arguing that the missile theory is "scientifically impossible" and "illogical" because several domestic and foreign flights were in Iran at the same altitude of 8,000 feet.