At least 20 people, including several children, were killed after Syrian government helicopters dropped barrel bombs Monday on rebel-held areas in Aleppo, according to the Syrian Observatory for Human Rights.

The attacks occurred in Aleppo’s Sukkari neighborhood, according to Al Arabiya. Helicopters also dropped barrel bombs Sunday night in Aleppo province, killing a woman in the Al Sheikh Fares neighborhood and injuring an unknown number of people.

Syrian President Bashar Assad’s regime is fighting a number of rebel groups, including the Islamic State of Iraq and Syria and the Al-Nusra Front, an al-Qaida affiliated group.

One ISIS fighter was killed Sunday in clashes between the militant group and Syrian Kurdish forces in the southwest Syrian village Ayn Al Arab. Another ISIS member was killed in fighting in the village of Tal Ayyub, according to the human rights group.