There is more information Thursday morning about the plane crash that killed 176 people in Iran.
Among the dead are two professors from The University of Alberta in Canada and their young daughters.
The plane never made a radio call for help and was trying to turn back for the airport when it went down, according to the initial Iranian investigative report.
Iranian officials are refusing to share the critical black box information from that plane, which is leading to speculation as to whether the plane suffered mechanical issues or was shot down.
Canadian Prime Minister Justin Trudeau said he's not ruling anything out.
The 3-year-old plane passed a safety inspection just two days before the tragedy.
Thursday morning, Ukrainian International Airlines announced an indefinite suspension of all flights to Iran.