A Malaysia Airlines plane carrying 295 people was reportedly shot down by a surface-to-air missile near the Russia-Ukraine border.
Ukrainian authorities report there are no survivors. Both Russian and Ukrainian officials deny responsibility.
As the wreckage continued to burn, an Associated Press journalist counted at least 22 bodies at the crash site, about 25 miles from the Russian border.
What does this mean for the conflict between Russia and Ukraine? CBN International News Reporter George Thomas, who has reported extensively on the conflict, answers this and more. Click play to watch.
Ukrainian adviser Anton Gerashenko said the jet, which was on its way from Amsterdam to Kuala Lumpur, was in the Donetsk region - the epicenter of the Ukrainian conflict - when it went down.
In the past week, Ukraine claimed Russia shot down two government planes.
Pro-Russia rebels reportedly bragged on their Facebook page that they shot down a Ukrainian cargo plane at the same time Malaysia reported losing contact with Flight MH17.
Pro-Russia rebels were seen by an Associated Press reporter a few days ago with a buk, surface-to-air missile system. It can fire a missile up to 72,000 feet into the air. The plane was flying at 33,000 feet.
Ukrainian President Petro Poroshenko said his country did not shoot down any planes.
"We do not exclude that this plane was shot down, and we stress that the Armed Forces of Ukraine did not take action against any airborne targets," he said. "We are sure that those who are guilty in this tragedy will be held responsible."
The news comes after the United States and the European Union imposed new economic sanctions against Russia Wednesday for its involvement in the fighting in Ukraine.
President Barack Obama announced the penalties, which target two major Russian energy firms, a pair of powerful financial institutions, and eight arms companies.
Obama said Russian leaders must see that their actions supporting rebels "have consequences."
"What we are expecting is that the Russian leadership will see once again that its actions in Ukraine have consequences, including a weakening Russian economy and increasing diplomatic isolation," Obama said from the White House.