US Vice President Joe Biden said on Thursday it appeared that the downing of a Malaysian airliner near the Ukraine-Russia border was not an accident and that the passenger jet apparently was "blown out of the sky."
"This is truly a grave situation," Biden said in a speech in Detroit.
He said he had seen reports that Americans may have been on board and that "we're now working every minute to try to confirm those reports as I speak."
Biden said the downing of the jet was tragic. He spoke by phone to Ukraine President Petro Poroshenko.
Speaking of what happened to the plane, Biden said: "We don't have all the detail yet. I want to be sure of what I say." He said the aircraft "apparently has been shot down - shot down, not an accident, blown out of the sky."
Biden added: "Nearly 300 souls have been lost. The families need consolation and our prayers. And there are many questions that need to be answered, and we’ll get those answers. And we will take the next steps accordingly."