Pro-Russia separatists shot down a Ukrainian military transport plane today, killing all 49 people on board.

Only a week after Ukraine's new President, Petro Poroshenko, spoke of a plan for peace in his inaugural address, Ukrainian forces have experienced the deadliest single incident yet in their battle against armed separatists.

Ukraine's defense ministry issued a statement saying that the plane, which was transporting military personnel, was shot down by insurgents using anti-aircraft machine guns.

According to the AP, Poroshenko called an emergency meeting of Ukraine's national security council:

Afterward, the president scolded the head of the country's SBU security service, referring to "omissions" in measures to protect military aircraft from attack. He called for "a detailed analysis of the reasons" and hinted that personnel changes were imminent.

The AP has video of the wreckage:

Poroshenko has declared Sunday a day of national mourning.

[image via AP]