Around the time the plane crashed, Russian media quoted witnesses as saying they saw a plane being hit by what they thought was a rocket.
It was the second time that a Malaysia Airlines plane was lost in less than six months. Malaysia Airlines Flight 370 disappeared in March while en route from Kuala Lumpur to Beijing. It has not been found, but the search has been concentrated in the Indian Ocean far west of Australia.
Dutch Prime Minister Mark Rutte, who had been attending a European Union summit in Brussels, headed back to the Netherlands to deal with the crash.
In Kuala Lumpur, several relatives of those onboard the Malaysian airliner came to the international airport.
A distraught Akmar Mohamad Noor, 67, said her older sister was coming to visit the family in Kuala Lumpur for the first time in five years.
"She called me just before she boarded the plane and said 'see you soon,'" Akmar said.
There have been several disputes over planes being shot down over eastern Ukraine 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. 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.
Russia's U.N. Ambassador Vitaly Churkin told reporters at U.N. headquarters in New York on Thursday that Russia did not shoot down the Ukrainian fighter jet on Wednesday. "We didn't do it," Churkin said.
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.
Earlier this week, Ukraine said a military transport plane was shot down Monday over eastern Ukraine by a missile fired from Russian territory.
Flights that were airborne when the Malaysia Airlines jet crashed have been re-routed, transportation officials said.
Peter Leonard reported from Kiev with contributions from an Associated Press reporter in Hrabove. Also contributing to this report were AP Airlines Writer Scott Mayerowitz in New York; Jill Lawless and Matthew Knight in London; Laura Mills and Jim Heintz in Moscow; Darlene Superville in Washington; Mike Corder in The Hague, Netherlands, and Eileen Ng and Satish Cheney in Kuala Lumpur, Malaysia.
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