BEIRUT (AP) — Syrian activists say Islamic State fighters have broken through defenses and taken over at least part of a military air base that is the last government-held outpost in a northeastern province dominated by the extremist group.

The center of Islamic State power in Syria. (Image via Google Maps.)

The center of Islamic State power in Syria. (Image via Google Maps.)

The Britain-based Syrian Observatory for Human Rights says clashes are still raging Sunday for control of the Tabqa air base, some 45 kilometers (25 miles) from the Islamic State group’s powerbase in the city of Raqqa.

Another activist group, the Local Coordination Committees, says the jihadis have taken full control of the airfield.

The extremists launched their long-anticipated offensive to seize Tabqa last week. The Observatory says at least 100 Islamic State group fighters have been killed and 300 wounded in the fighting. It puts regime dead at 25.