Russia suffered the biggest single loss of life of its 10 -monthlong mission in Syria when five people died in a military helicopter that was shot down after delivering aid.

The Mi-8 transporter arrived under flame from the ground in Syrias north-western Idlib province as it was returning to the Hmeimeen air base after delivering humanitarian aid to the city of Aleppo, the Russian Defense Ministry said in an e-mailed statement Monday. Three crew and two officers from the Russian Center for Reconciliation in Syria were on board, government ministries said.

Wreckage of Russian military helicopter in Aleppo .
Photographer: Firas Faham/ Anadolu Agency/ Getty Images