That was the question on the lips of people throughout the world yesterday.
It was one of many. How? Why? Who?
There were no immediate answers.
The deaths of 298 people aboard Malaysia Airlines flight MH17, shot down yesterday over eastern Ukraine, caused an international outpouring of grief, anger and confusion.
The Malaysia Airlines Boeing 777 was flying from Amsterdam to Kuala Lumpur when what US intelligence authorities believe was a surface-to-air missile brought it down.
Who fired the missile is still not clear, but Britain said today it was increasingly likely that separatists in eastern Ukraine were to blame.
A US official yesterday said Washington strongly suspected the aircraft was downed by a sophisticated Buk surface-to-air missile fired by Ukrainian separatists backed by Moscow.
A spokesman for Prime Minister David Cameron said the evidence suggested that separatists had shot down the airliner with a surface-to-air missile fired from Torez, in an area of eastern Ukraine controlled by pro-Russian separatists.
Among the victims were a New Zealand woman - a longtime resident of Australia - and a British citizen who had been living in New Zealand. Also killed were 28 Australians.
Most of the dead, 173 people, were Dutch. Twenty-eight were Malaysian, 12 Indonesian, nine British, four German, four Belgian, three Filipino and one from Canada. All 15 crew were Malaysian. Nationalities of the others on board were unclear.
World leaders demanded an international investigation as Kiev and Moscow blamed each other for a tragedy that stoked tensions between Russia and the West.
There were no survivors from yesterday's crash, which left wreckage and bodies scattered across miles of rebel-held territory.
The scale of the disaster could prove a turning point for international pressure to resolve the crisis in Ukraine, which has killed hundreds since protests toppled the Moscow-backed president in Kiev in February and Russia annexed the Crimea a month later.
The United States called for an immediate ceasefire to allow easy access to the crash site, while pro-Russian separatists told the Organisation for Security and Co-operation in Europe, a security and rights body, they would ensure safe access for international experts visiting the scene.
The plane crashed about 40km from the border with Russia, near the regional capital of Donetsk, an area that is a stronghold of rebels who have been fighting Ukrainian government forces.
Leaders of the rebel Donetsk People's Republic denied any involvement and said a Ukrainian air force jet had brought down the intercontinental flight.
Reuters journalists saw burning and charred wreckage bearing the red and blue Malaysia Airlines insignia and dozens of bodies in fields near the village of Grabovo.
''While we do not yet have all the facts, we do know that this incident occurred in the context of a crisis in Ukraine that is fuelled by Russian support for the separatists, including through arms, materiel, and training,'' White House spokesman Josh Earnest said in a statement.
US Vice-president Joe Biden said it appeared the downing of the jetliner was not an accident and that it apparently was ''blown out of the sky''.
A tough-talking Prime Minister Tony Abbott pointed blame at Russia, going further than other Western leaders, demanding yesterday that Moscow answer questions about the ''Russian-backed rebels'' that he said were behind the disaster.
In a sombre speech, Mr Abbott said the world should be ''filled with revulsion''.
Some of those on board were travelling to an international Aids conference in Melbourne, including Joep Lange, an influential Dutch expert.
The Independent reported two Newcastle United fans travelling to New Zealand were also feared to be among the victims. The fans' website, NUFC.com, said John Alder, in his 60s, and Liam Sweeney (28) planned to watch their team play in a pre-season tour that starts in Dunedin on Tuesday.
''I was working in the field on my tractor when I heard the sound of a plane and then a bang,'' a man said in Grabovo (locally called Hrabove).
''Then I saw the plane hit the ground and break in two. There was thick black smoke.''
The loss of MH17 is the second devastating blow for Malaysia Airlines this year, following the mysterious disappearance of flight MH370 in March, which vanished with 239 passengers and crew on its way from Kuala Lumpur to Beijing.
In Malaysia, there was a sense of disbelief that another airline disaster could strike so soon.
''If it transpires that the plane was indeed shot down, we insist that the perpetrators must swiftly be brought to justice,'' Malaysian Prime Minister Najib Razak said.
''This is a tragic day, in what has already been a tragic year for Malaysia.''
Ukraine accused pro-Moscow militants, aided by Russian military intelligence officers, of firing a long-range, Soviet-era SA-11 ground-to-air missile.
Russian President Vladimir Putin - at loggerheads with the West over his policies towards Ukraine - pinned the blame on Kiev for renewing its offensive against rebels two weeks ago after a ceasefire failed to hold.
''There is no doubt that the country on whose territory this terrible tragedy happened bears responsibility,'' he said.
US President Barack Obama said evidence from the crash must remain in Ukraine so international investigators have a chance to look at it.
Kiev complained separatists prevented Ukrainian officials from reaching the site.
Separatists said yesterday they had found one of the flight recorders, and a Reuters cameraman at the scene said rescue workers had recovered a second flight recorder.
A Ukrainian military cargo plane and a fighter jet crashed this week in separate incidents as Ukrainian forces clashed with separatists, raising concerns the separatists could be armed with sophisticated anti-aircraft weapons.
- Agencies
