Syrian rebels on Friday seized a state air defense base east of the northern city of Aleppo, as government forces fought militants across the country, Qatar-based broadcaster Al Jazeera quoted activists as saying.

The air defense base was located in al-Tana village on the road east from Aleppo to al-Raqqa, it quoted the Syrian Observatory for Human Rights as saying on Friday.

Clashes were also occurring at other locations. The Britain-based pro-opposition Observatory said rebels killed over 100 soldiers in two days.

The Syrian conflict has claimed tens of thousands of lives, according to various Syrian opposition groups. The UN puts the death toll at over 20,000 people.

The West is pushing for President Bashar al-Assad’s ouster while Russia and China are trying to prevent outside interference in Syria, saying that the Assad regime and the opposition are both to blame for the bloodshed.