DAMASCUS, Feb. 11 (Xinhua) -- At least 16 people were killed Monday by a U.S.-led airstrike in eastern Syria, a war monitor reported.

Half of the deaths were children, who lost their lives as a result of the U.S.-led shelling on the Islamic State (IS)-held areas on the outskirts of the Baghouz town in the eastern countryside of Deir al-Zour province, said the Syrian Observatory for Human Rights.

The shelling also led to the killing of 28 IS militants.

The attack is the latest in a string of airstrikes targeting the last IS-held pocket in the eastern Euphrates river region.

Earlier in the day, state news agency SANA said four civilians were killed by U.S.-led airstrikes on the same area.

On Saturday, the U.S.-backed Syrian Democratic Forces (SDF) started on the final stage of attacks against the IS in the eastern Euphrates river region in eastern Syria.

Following the evacuation of over 20,000 civilians from the town of Baghouz, the SDF started on Saturday night the operation against the remaining IS-held pocket in the eastern Euphrates region, according to Mustafa Balli, the head of the SDF media office.

Balli said that the battle aims to eliminate the last IS militants in the town of Baghouz.

After losing the four sq km, the IS will still be in control of 4,000 sq km in the Syrian desert in eastern Syria.

The SDF have been on a crushing offensive to root out IS from the eastern Euphrates region since last September and managed, with the help of the U.S., to defeat IS in much of the areas it had controlled in the eastern Euphrates area.

The Syrian Observatory for Human Rights said over 37,000 civilians, including tens of IS militants, have fled the last IS-held pocket to areas controlled by the SDF in the eastern Euphrates area since last December.