Reports out of Moscow confirm a Russian military transport aircraft crashed in Syria on Tuesday. All 26 passengers and six crew members are confirmed dead. Everyone on board was Russian military personnel.

The Antonov An-26 dual prop transport and cargo aircraft reportedly crashed as it was approaching a runway at Russia’s Khmeimim airbase in the Latakia province. The aircraft was making its approach, when it abruptly lost altitude and collided into the ground 1600 feet short of the runway. Initial indicators say that the failure may have been technical or pilot-based in nature, as there has been no evidence to suggest terror activity and the aircraft was not under fire during its approach.

According to the Russian Defense Ministry statement regarding the incident, an investigation into the cause of the crash is already underway, though no further details were available at this time.

This incident marks a significant uptick in the deaths of Russian troops the Kremlin has been willing to acknowledge since they began offering direct military support to Syrian President Bashar al Assad in 2015. According to official statements from the Russian government, about 46 Russians had been killed in Syria since then, prior to Tuesday’s incident, though most experts agree that Russian casualties have gone significantly underreported.