BREAKING: Malaysian jet crashes - possibly shot down over Ukraine.

Interfax news agency reports that a Malaysian jet has crashed in eastern Ukraine, near the Russian border. The Malaysian Airlines passenger plane had 295 people on board and was on its way from Amsterdam to Kuala Lumpur.

Anton Gerashenko, an adviser to Ukraine's Interior Minister, wrote on Facebook that the plane was hit by a missile fired from a Buk launcher over the country's east, the Associated Press reports.

Malaysia Airlines confirmed it had lost contact with flight MH17 and that its last position was over Ukrainian airspace.

A Russian aviation industry source told Reuters that the plane did not enter Russian airspace when expected.

Ukraine's east has seen heavy fighting between the country's military and separatists in recent days. Earlier on Thursday, the Ukrainian military claimed Russian jets had shot down a Ukrainian warplane late Wednesday night.

More from the Associated Press:

KIEV, Ukraine (AP) — A Ukrainian official said a passenger plane carrying 295 people was shot down Thursday over a town in the east of the country, and Malaysian Airlines tweeted that it lost contact with one of its flights over Ukrainian airspace.

Anton Gerashenko, an adviser to Ukraine's interior minister, said on his Facebook page the plane was flying at an altitude of 10,000 meters (33,000 feet) when it was hit by a missile fired from a Buk launcher. A similar launcher was seen by Associated Press journalists near the eastern Ukrainian town of Snizhne earlier Thursday. The Buk missile system can fire missiles up to an altitude of 22,000 meters (72,000 feet).

Malaysia Airlines said on its Twitter feed that it "has lost contact of MH17 from Amsterdam. The last known position was over Ukrainian airspace. More details to follow."

The region has seen severe fighting between Ukrainian forces and pro-Russia separatist rebels in recent days.

On Wednesday evening, a Ukrainian fighter jet was shot down by an air-to-air missile from a Russian plane, Ukrainian authorities said Thursday, adding to what Kiev says is mounting evidence that Moscow is directly supporting the separatist insurgents in eastern Ukraine. Security Council spokesman Andrei Lysenko said the pilot of the Sukhoi-25 jet hit by the air-to-air missile was forced to bail after his jet was shot down.

Pro-Russia rebels, meanwhile, claimed responsibility for strikes Wednesday on two Ukrainian Sukhoi-25 jets. The Ukrainian Defense Ministry said the second jet was hit by a portable surface-to-air missile, but added the pilot was unscathed and managed to land his plane safely

Moscow denies Western charges that is supporting the separatists or sowing unrest in its neighbor. The Russian Defense Ministry couldn't be reached for comment Thursday about the Ukrainian jet and Russia's foreign ministry didn't respond to multiple requests for comment.

Earlier this week, Ukraine said a military transport plane was shot down Monday by a missile fired from Russian territory.

The rebels are known to possess portable anti-aircraft rocket launchers, but Ukrainian officials say that kind of weapon would have been unable to reach Monday's plane at the altitude at which it was flying Monday. Aviation experts, however, have questioned whether the stricken transport plane was flying at the altitude Ukrainian officials had claimed.