The United States believes a surface-to-air missile brought down a Malaysia airliner that crashed in eastern Ukraine, killing all 298 people on board, an incident that sharply raises the stakes in a conflict between Kiev and pro-Moscow rebels.
There were conflicting claims of responsibility after the shocking new development in crisis-torn Ukraine, where fighting between separatists and the Western-backed government has claimed over 600 lives.
Here's what is known, and what has been claimed about Thursday's crash of a Malaysia jetliner MH17:
A Malaysia Airlines Boeing 777-200ER, which the carrier said was carrying 283 passengers, including three infants, and 15 crew members on Flight MH17 from Amsterdam to Kuala Lumpur, Malaysia. After leaving Amsterdam at 12:15 pm local time, the aircraft was due to land at Kuala Lumpur International Airport at 6:10am local time the following day.
Though Ukrainian military aircraft have been shot down over eastern Ukraine by rebels, and the area has been the scene of fierce fighting, the route taken by the Malaysia jet appears to have been subject to no flight restrictions, the International Air Transport Association, an industry group, said. Eurocontrol, a European air safety organisation, said the plane apparently was flying at approximately 10,000 meters (33,000 feet), which was authorised, although Ukrainian authorities had closed the airspace at lower altitudes.
Malaysia Airlines said it was notified by Ukrainian authorities that they lost contact with the plane when it was 30 kilometers (18 miles) from the Tamak waypoint, approximately 50 kilometers (30 miles) from the Ukraine-Russia border. The plane-tracking service FlightAware.com said the last reported position for MH17 was at 33,000 feet just west of Ukraine's border with Russia.
Who shot it down
One US official said Washington strongly suspected a surface-to-air missile that downed the Malaysia airliner was fired by Ukrainian separatists backed by Moscow.
There was no evidence Ukrainian government forces fired a missile, said the official, speaking on condition of anonymity.
Ukraine accused pro-Moscow militants, aided by Russian military intelligence officers, of firing a long-range, Soviet-era SA-11 ground-to-air missile.
Read: Malaysia airliner downing puts spotlight on Buk missile system
Leaders of the rebel Donetsk People's Republic denied any involvement and said a Ukrainian air force jet had brought down the intercontinental flight.
Shot by mistake?
A flurry of comments on social media by pro-Russia rebel chief claiming they had shot down a Ukrainian army plane in the exact spot the Malaysia plane went down were hastily removed as they appeared to realise their error.
Comments attributed to a pro-Russia rebel chief had reportedly suggested his men may have downed Malaysia Airlines flight MH17 by mistake, believing it was a Ukrainian army transport plane.
Read: International probe demanded after MH17 downed over eastern Ukraine
Was Buk 9k37 missile system used?
A launcher similar to the SA-17 missile system, also known as Buk 9k37 missile system, was seen by AP journalists earlier Thursday near the eastern Ukrainian town of Snizhne, which is held by the rebels.
Who said what
An adviser to Ukraine's interior minister said the plane was shot down with a missile, but gave no proof.
In a counterclaim, a pro-Moscow separatist leader said he was certain that it was Ukrainian troops who downed the airliner, but also offered no explanation or proof.
Ukrainian President Petro Poroshenko denied his country's armed forces fired on any aerial targets Thursday.
Independent Western defense experts told the AP that both Ukrainian and Russian armed forces possess SA-17 missile launchers capable of reaching an altitude of 20,000 meters (66,000 feet), and that pro-Moscow insurgents may have gotten their hands on one to two surface-to-air missiles when Ukrainian forces retreated.
Russian President Vladimir Putin - at loggerheads with the West over his policies toward Ukraine - pinned the blame on Kiev for renewing its offensive against rebels two weeks ago after a ceasefire failed to hold. The Kremlin leader called it a "tragedy" but did not say who brought the Boeing 777 down.
Read: Kiev 'bears responsibility' for Malaysia plane crash, says Putin
Two US officials told AFP that intelligence analysts were reviewing the data to see whether the missile used to down the aircraft was launched by pro-Moscow separatists, Russian troops across the border or Ukrainian government forces.
"We are working through all the analysis," said one official, adding that there was little doubt that the plane was struck by a surface-to-air missile.
In Detroit, US Vice President Joe Biden said the plane was "apparently... and I say apparently because we don't have all the details yet... shot down. Not an accident. Blown out of the sky."
Australian Prime Minister Tony Abbott blamed Russia on Friday over the shooting down of a Malaysia Airlines passenger jetliner over eastern Ukraine that killed all 298 people on board.
Abbott appeared to go further than other Western leaders in apportioning blame over the crash, demanding that Moscow answer questions about the "Russian-backed rebels" that he said were behind the disaster.
The shooting down of civilian aircraft is extremely rare, and if proved the case, the downing of the MH17 would be one of the deadliest yet. In 1988, 290 were killed when an Iran Air plane was shot out of the sky and 269 died when Soviet fighter jets downed a South Korean Boeing 747 in 1983.
(With inputs from Reuters, AFP, AP)