The Boeing 777-200 disappeared from radar at about 2.15pm local time (12.15am Australian EST) as it flew at an altitude of 33,000 feet.
The plane was hit by a surface-to-air missile as it travelled over the village of Grabovo in the Ukraine near the Russian border. Debris and bodies scattered across several miles, with no presumed survivors.
The presumed death toll
Malaysia Airlines has updated the official passenger list to 283, up from the previous 280.
Foreign Minister Julie Bishop has confirmed that 27 Australians were on board.
The Ukrainian Goverment has said that it understands delegates bound for an AIDS conference in Melbourne were on the flight.
Who shot down the plane?
There is growing speculation that a Russian separatist movement was behind the shooting, although Ukrainian, Russian and rebel leaders have denied involvement.
Ukrainian President Petro Poroshenko has said he believed a “terrorist act” was responsible, as The UN Security Council organised an emergency meeting for Friday morning.
Comments attributed to a top Ukrainian rebel commander suggest the separatists shot down the plane by mistake, believing it was a large Ukrainian army transport plane.
The intercepted conversation, released by Ukraine’s Security Service, is allegedly between Pro-Russian separatists and the Russian military.
“We have just shot down a plane. Group Minera. It fell down beyond Yenakievo,” reads the translated conversation. “It’s 100 per cent a passenger aircraft.”
News website Mashable is reporting that one of its journalists spoke briefly with Alexander Borodai, self-declared prime minister of Donetsk People’s Republic, after the crash.
Mr Borodai reportedly said, “Look, we don’t have these weapons”, then hung up.
— Flightradar24 (@flightradar24) July 17, 2014
Social media furor
Ukrainian supporters are pointing to social media as proof of rebel involvement.
Commander of the Russian separatists Igor Strelkov, who is widely known by the pseudonym ‘Igor Girkin’, boasted on VK.com (Russia’s version of Facebook) 30 minutes after the plane disappeared.
“We have warned them. Do not fly in our sky,” is a translation of the post from the self-proclaimed defence minister of the Donetsk People’s Republic.
The post has since been deleted, but is archived here.
Mr Strelkov has since posted an explanation, saying that the news was taken from another social media forum, and was not an official statement from the Donetsk People’s Republic. He also denied any rebel involvement in the crash.
Independent Western defence experts say both Ukrainian and Russian armed forces possess SA-17 missile launchers capable of reaching an altitude of 20,000 metres (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.
A launcher similar to the SA-17 missile system, also known as Buk, was seen by AP journalists earlier on Thursday near the eastern Ukrainian town of Snizhne, which is held by the rebels.
Why was the plane in the area?
There is dispute over whether this plane should have been flying over eastern Ukraine at all. It was travelling above rebel-held territory near Donetsk where Pro-Russian separatists have shot down several aircraft in recent weeks.
As recently as Thursday, a Ukrainian fighter jet was reportedly shot down. A military transport plane was also downed on Tuesday, according to the Ukrainian Government.
Malaysian Prime Minister Razak has said that the route was declared safe by the International Civic Aviation Organisation (ICAO).
The ICAO has now formally closed airspace in the east of Ukraine, prompting questions as to why it had not taken this action sooner.
What was used?
There is speculation that a Soviet-built Buk surface-to-air missile was used.
This is because MH17 was reportedly flying at 30,000 feet. Helicopters and aircraft shot down by rebels in recent weeks were downed by shoulder-fired portable missiles, which would not have been able to reach this height.
The other possibility is that a jet fighter, under the control of either Ukrainian or Russian, shot down the flight. But as yet there is no indication of any military aircraft in the area at the time.
The recovery begins
Separatist rebels and locals have begun tentative recovery efforts, bringing fire engines to put out blazes.