What we know:

Malaysia Airlines Flight 17 came down in eastern Ukraine, near Donetsk

Ukrainian President Petro Poroshenko calls it a "terrorist action"

A Ukrainian interior ministry official says the plane was "shot down"

Investigation has begun, with some experts cautioning that it must involve parties not involved in the ongoing Ukraine-Russia strife

There were 280 passengers and 15 crew on board, flying from Amsterdam to Kuala Lumpur