BEIRUT - Airstrikes by the U.S.-led coalition have hit a Syrian oil refinery held by the Islamic State group, activists said Monday.

The strikes targeted a refinery near the Turkish-Syrian border outside the town of Tel Abyad. Video from the Turkish Dogan News Agency showed the strikes Sunday night, which saw an enormous fireball engulf the refinery.

The Britain-based Syrian Observatory for Human Rights estimated the strikes killed about 30 people, including Islamic State militants and refinery workers. The Syrian activist group Raqqa is Being Slaughtered Silently also reported the strikes, but offered no casualty figure.

The Islamic State group, which controls a self-declared caliphate on captured territory covering about a third of Syria and Iraq, partially funds its conquests through the sale of black market oil.

The U.S.-led coalition did not immediately acknowledge launching the strike.