The coalition of militias known as Libya Dawn launched airstrikes against the Islamic State group in Sirte, Libya Thursday. Above, Libya Dawn fighters fire artillery at Islamic State militants near Sirte, March 19, 2015. Reuters/Goran Tomasevic

Fajr Libya, the coalition of militias controlling the Libyan capital of Tripoli, launched airstrikes against the Islamic State group in the Mediterranean city of Sirte late Thursday, an official in the city said Friday.

Fajr Libya, which means Libyan Dawn, targeted several positions held by the Islamic State, including a command base, in Sirte, Agence France-Press reported. Troops with Fajr Libya and the Islamic State, also known as ISIS, had been fighting in Sirte since Wednesday evening, a spokesman for the coalition told AFP. Militants from both groups have been clashing sporadically since mid-March.

ISIS in Libya has released a number of videos in recent months appearing to show brutal executions of Christians. On Sunday, it published a video in which militants appeared to behead and shoot dozens of Ethiopian Christians. In February, the group released a video showing the beheadings of more than a dozen Egyptian Coptic Christians on a beach in Libya.

Fajr Libya, which took control of Tripoli in August and set up a government and parliament there, is not internationally recognized, while the internationally recognized but relatively powerless government has fled to a small city in eastern Libya known as Bayda. Fajr Libya's coalition includes Islamist groups.

ISIS’ presence in Libya dates back to September 2014. It started off in the eastern city of Derna, along Libya’s Mediterranean coast and close to the Egyptian border, and by January the group had expanded to Sirte, a city about 530 miles away and the hometown of former Libyan dictator Moammar Gadhafi. In 2011 after 42 years in power, Gadhafi was deposed by a popular rebellion aided by airstrikes from the international community, leaving a power vacuum that has allowed for the chaotic rise of militant groups and extremists in the country.