Story highlights Airstrikes hit two separate cities in Syria on Sunday

An estimated 400,000 civilians have died since the Syrian conflict started in 2011

(CNN) Airstrikes and shelling killed at least 57 people Sunday in two separate towns in Syria, according to the UK-based Syrian Observatory For Human Rights (SOHR).

The continued fighting on Sunday came two days before a fresh round of United Nations-facilitated peace talks were to start Tuesday in Geneva, to be followed by a second session in December.

In the ISIS-held village of al-Shaafa, in Syria's eastern Deir Ezzor province, Russian airstrikes killed 34 civilians, including 15 children, SOHR said in a statement.

Al-Shaafa sits on the eastern bank of the Euphrates River, one of the last areas occupied by ISIS in the region.

Many of those wounded in the airstrike are in critical condition, which could cause the death toll to rise, SOHR added.

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