GRABOVO, Ukraine — A Malaysia Airlines Boeing 777 with 298 people aboard exploded, crashed and burned on a flowered wheat field Thursday in a part of eastern Ukraine controlled by pro-Russia separatists, blown out of the sky at 33,000 feet by what Ukrainian and American officials described as a Russian-made antiaircraft missile.

Ukraine accused the separatists of carrying out what it called a terrorist attack. American intelligence and military officials said the plane had been destroyed by a Russian SA-series missile, based on surveillance satellite data that showed the final trajectory and impact of the missile but not its point of origin.

There were strong indications that those responsible may have errantly downed what they had thought was a military aircraft only to discover, to their shock, that they had struck a civilian airliner. Everyone aboard was killed, their corpses littered among wreckage that smoldered late into the summer night.

Russia’s president, Vladimir V. Putin, blamed Ukraine’s government for creating what he called conditions for insurgency in eastern Ukraine, where separatists have bragged about shooting down at least three Ukrainian military aircraft. But Mr. Putin did not specifically deny that a Russian-made weapon had felled the Malaysian jetliner.