NOVOHANNIVKA, Ukraine — Pro-Russia separatists shot down a Ukrainian military transport plane Saturday, killing all 49 crew and troops aboard in a bloody escalation of the conflict in the country’s restive east.

Nine crew and 40 troops were aboard the Il-76 when it went down early Saturday as it approached the airport at Luhansk, the Ukrainian prosecutor general’s office said. The Russian-built Il-76 is a four-engine jet used to transport heavy gear and people.

Luhansk is in eastern Ukraine near the border with Russia, an area where separatists have seized government buildings and declared independence after holding disputed referendums. Ukrainian forces still control the Luhansk airport, however.

Defense Ministry spokesman Bohdan Senyk said the rebels used anti-aircraft guns and a heavy machine gun to down the plane, while the prosecutor general’s office mentioned an anti-aircraft missile.

It was a bitter setback for the Ukrainian forces, which have struggled to suppress an armed insurgency by foes of the new government. And it came only a week after Ukraine’s new president, billionaire candy magnate Petro Poroshenko, spoke about a peace plan in his inaugural address.

Yet the deadliest single incident in the four-month-old conflict suggested the two sides were still far apart in their demands and talk of de-escalating the conflict remained premature.