A Ukrainian airliner carrying at least 176 people crashed shortly after takeoff from Tehran on Wednesday, killing everyone on board.

It was unclear what caused the disaster, but the aircraft, a Boeing 737-800, went down amid an escalating, violent conflict between the US and Iran.

Among the victims were 82 Iranians, 63 Canadians, 11 Ukrainians, 10 Swedes, three Germans and three Britons, Ukrainian foreign minister Vadym Prystaiko said.

Early statements from both Ukraine and Iran about what happened to the flight bound for Kiev, the Ukrainian capital, were both confused and contradictory. Just hours earlier, Iran had fired missiles at two bases in Iraq that house US troops.

Though the evidence remained sketchy, aviation experts said that what was known indicated that the plane could have been attacked. Investigators should have that possibility “at the top of their agenda”, said Peter Goelz, a former managing director of the National Transportation Safety Board in the US.

The state-run Iranian Students’ News Agency shared a video it said showed the predawn crash, with an aircraft, apparently in flames, descending in the distance before a bright burst filled the sky upon impact.

Ukraine International Flight 752 left Imam Khomeini International Airport in Tehran at 6.12am on Wednesday and abruptly ceased the automatic transmission of flight data about two to three minutes later, though it remained in the air for a few minutes longer.

Experts say that is an extremely rare sequence of events, even in a catastrophic accident — and all the more unexpected in a relatively new plane, built in 2016, of a model with a very good safety record.