(CNN) — Fierce battles continue around the strategic city of Deir Ezzor in northern Syria between regime forces and the Islamic State in Iraq and Syria (ISIS), according to human rights groups.
Hundreds of combatants and civilians have been killed over the past week, and Russian aircraft have been dropping supplies to beleaguered army units.
The regime of President Bashar al-Assad is battling to retain a foothold in the area. It still controls the military airport to the south, but ISIS claims to have overrun several regime-held districts at the beginning of the week, taking advantage of a sandstorm that grounded military aircraft. But in the last few days, Russian and possibly Syrian warplanes have carried out airstrikes against ISIS areas, while the already desperate situation of civilians has worsened.