Initial report on Ukrainian plane crash in Iran released

The crew of a Ukrainian jetliner that crashed in Iran never made a radio call for help and were trying to turn back for the airport when the plane went down, according to an initial Iranian report released Thursday on the disaster that killed 176 people.

The report suggested a sudden emergency struck the Boeing 737 operated by Ukrainian International Airlines early Wednesday morning, when it went down just moments after taking off from Imam Khomeini International Airport in Tehran.

Also watch: Plane exploded before crashing in Iran

Investigators from Iran's Civil Aviation Organization offered no immediate explanation for the disaster, however.

Eyewitnesses, including the crew of another passing flight, described seeing the plane engulfed in flames before crashing, the report said. The crash caused a massive explosion when the plane hit the ground, likely because the aircraft had been fully loaded with fuel for the flight to Kyiv, Ukraine.

The report also confirmed that both of the so-called 'black boxes' that contain data and cockpit communications from the plane had been recovered, though they had damaged and some parts of their memory was lost. It also said that investigators have initially ruled out laser or electromagnetic interference as causing the crash.

Ukrainian President Volodymyr Zelenskiy, meanwhile, said crash investigators from his country had arrived in Iran to assist in the probe. He also said he planned to call Iranian President Hassan Rouhani about the crash and the investigation.

"Undoubtedly, the priority for Ukraine is to identify the causes of the plane crash," Zelenskiy said. "We will surely find out the truth."

The plane was carrying 167 passengers and nine crew members from several countries, including 82 Iranians, at least 63 Canadians and 11 Ukrainians, according to officials. The crash just before dawn scattered flaming debris and passengers' belongings across a wide stretch of farmland. It also came immediately after Iran launched a ballistic missile attack against Iraqi military bases housing US troops amid a confrontation with Washington over it killing an Iranian Revolutionary Guard general in a drone strike last week.

Many of the passengers were believed to be international students attending universities in Canada; they were making their way back to Toronto by way of Kyiv after visiting with family during the winter break.

Canadian Prime Minister Justin Trudeau said 138 of the passengers were bound for Canada. The flight also included a family of four and newlyweds, too. The manifest listed several teenagers and children, some as young as 1 or 2.

The crash ranked among the worst losses of life for Canadians in an aviation disaster. The flag over Parliament in Ottawa was lowered to half-staff, and Trudeau vowed to get to the bottom of the disaster.

"Know that all Canadians are grieving with you," he said, addressing the victims' families.

Ukrainian officials, for their part, initially agreed with Iranian suspicions that the 3½-year-old plane was brought down by mechanical trouble but later backed away from that and declined to offer a cause while the investigation is going on.

Boeing extended condolences to the victims' families and said it stands ready to assist.