The Cougar helicopter crashed shortly after taking off from a base in Sirnak province bordering Iraq, killing all 13 onboard, it said in a statement.
"Our hero comrades in the helicopter fell as martrys," the army said.
Initial findings showed it was an accident, said the army, adding that an investigation was underway.
Turkey's chief of staff, General Hulusi Akar, travelled to the region to carry out an inspection, the state-run Anadolu news agency reported.
In a separate statement, the local governor's office said rescue teams had been dispatched to the scene.