A missile hit and a terrorist attack are among the suspected causes of the deadly crash of a Ukraine plane in Tehran on Wednesday, according to Ukrainian officials. 

The National Security and Defense Council of Ukraine (NSDC) said on Thursday that a third cause could be the engine explosion due to a technical glitch.

A NSDC statement said the trajectory of the aircraft showed the plane belonging to the International Airlines changed it route to return to the airport but pilots did not report any emergencies.

Iran's Civil Aviation Organization said Thursday the plane caught fire before hitting the ground.

The crash killed all 176 passengers onboard shortly after it took off from Tehran’s international airport. It came at a time the Iranian army launched tens of ballistic missiles targeting U.S. troops in Iraq.

Iran’s attack was a retaliation over the assassination of Iran's Quds Forces leader, Qasem Soleimani in a U.S. drone strike last week.

Among the victims were 82 Iranians, 63 Canadians, 11 Ukrainians, 10 Swedes, four Afghans, three Germans and three British citizens.