A passenger plane with 295 people on board has been shot down as it flew above eastern Ukraine, according to aviation sources.
The Malaysia Airlines plane, which was flying from Amsterdam to Kuala Lumpur, was travelling at an altitude of 10km (6.2 miles) when it was shot down, Russia's Interfax reported.
An adviser to the Ukrainian interior ministry said the Boeing 777 was brought down by a Buk ground-to-air missile.
All 280 passengers and 15 crew members who were on the plane are believed to have died, he added.
The Boeing 777 that crashed in eastern Ukraine. Pic: Andreas Fietz
A spokesman for Malaysian Airlines, still reeling from the loss of flight MH370 in March, confirmed it had lost contact with flight MH17, which took off from Amsterdam at 12.14pm local time.
The flight disappeared from radar as it flew over Ukrainian airspace, the spokesman said.
Ukrainian Prime Minister Arseniy Yatsenyuk ordered an immediate investigation into what he described as a "catastrophe", while his Malaysian counterpart Mohd Najib Tun Razak said he was "shocked".
Alexander Borodai, the eastern Ukraine separatist leader, claimed the airliner was shot down by Ukrainian government forces, although officials in Kiev denied any involvement.
The plane's last known position over Ukraine. Pic: Flightradar24/Twitter
There has been no official comment from authorities in Russia.
Sky's Katie Stallard, in Moscow, said media reports suggest the plane came down in the Donetsk region, where there has been recent heavy fighting amid continuing tensions between Russia and Ukraine.
Data from Flightradar24 suggests the plane had just passed the city of Kremenchuk, around 300km (186 miles) from the Russian border, when it disappeared.
Several videos apparently filmed in the area, none of which Sky News has been able to independently verify, show plumes of thick, black smoke rising high into the air.
A Reuters correspondent at the scene, close to the village of Grabovo, said he could see the wreckage of a burning aircraft and bodies on the ground.
Aviation expert Major Charles Hayman told Sky News: "It's highly likely this aircraft was flying along a fault line between Russian and Ukrainian defences.
"It’s possible the Ukrainians flapped a bit, thought it was hostile and shot it down.
"Perhaps it was confusion at the Ukrainian air defence centre.
"It looks like someone failed to recognise this was a civilian plane and shot it down."
A spokesman for Boeing said it was aware of reports of MH17's disappearance, while a Foreign Office official added: "We're urgently working to establish what has happened."
The White House said US President Barack Obama had spoken to his Russian counterpart Vladimir Putin and asked his advisers to keep him updated.
Disaster: Smoke billows into the sky after a Malaysia Airlines passenger plane was shot down over eastern Ukraine, killing all 295 people on board
I don't beleive it
A Reuters correspondent at the scene, close to the village of Grabovo, said he could see the wreckage of a burning aircraft and bodies on the ground
Reuter is the AP, which is owned by the Rothchilds... Why didn't he take pictures of the aircraft and bodies on the ground? Would probably be important photos. He might even win a prize or something. All cell phones have cameras...
More fake news to divert our attention and make us scared, and scared to fly. Fear based mind control. And no planes on 911, all CGI.
You idiot not everything is CGI and fake, http://www.kaotic.com/39422_War-Videos-First-Uncensored-Footage-Fro...
On its face, of course, just tragic. But damn, can't help but wonder if it is could be linked to the 370 flight. I still believe it was mistakenly/not so mistakenly shot down by NATO per the ongoing Asian Pivot debacle. Could be a signal to someone about something, anyway.
As the drama unfolded, several other passenger jets were flying through Ukrainian airspace on one of the main routes from Europe to Asia for air traffic.
He said: "Earlier today separatist fighters claimed to have shot down a Ukrainian Su-25 ground attack fighter in the area, so the goal may be to create a de-facto no-fly zone in the east of the country in a show of force after their ousting from Slovyansk.
"However, the aircraft will at that stage in its flight will have been cruising at a very high altitude – around 30,000 feet – so would have been well out of range of any shoulder-launched MANPADS weapons you might expect insurgent groups to possess.
Manpads, yes they are altitude limited. However the truck mounted surface to air types that the Russians have sent there, can and will reach 88,000 ft..
What I find unusual is, in both photos, the upper sky (especially in the smoke) appears to have been "Photoshopped".
yup, i see the pixelation on the smoke now that you mention it
This fake event is a good reason to increase security and take away our rights...PRS
Pictures I saw on Fox did not show any smoke or flame or aircraft parts in the sky prior to impact..Very doubtful it was hit by surface to air missile