Russian helicopter shot down in Syria, killing 5

MOSCOW — Rebels in Syria shot down a Russian combat helicopter Monday amid fierce fighting around Aleppo, killing all five people on board in the deadliest single incident for the Russian military since it became embroiled in Syria’s civil war 10 months ago.

The downing came as the Syrian army, under Russian air cover, fought to repel a rebel attempt to break the government’s siege of Aleppo, killing more than 800 militants, according to the Russian military.

International human rights groups have repeatedly accused Russia of hitting civilians and using cluster munitions since it began its aerial campaign in Syria.

The Russian military has denied hitting civilians, and also rejected claims that its aircraft targeted moderate elements of the Syrian opposition along with its declared targets, the Islamic State group and al Qaeda’s branch in Syria, the Nusra Front.