Libya has descended into chaos since Gaddafi's death REUTERS/Ismail Zitouny

Dozens of people have been killed in three apparent car suicide bombings in Libya's al-Qubbah, between Derna and Benghazi.

The blasts targeted the city's security directorate, a busy cafe' and a gas station.

A Benghazi photographer posted on Twitter pictures of the incident:

Motive behind the bombings are unclear. According to Saleh Aqila, speaker of Libya's House of Representatives, 30 civilians were killed in the attack. He announced seven days of mourning to commemorate the victims. Some speculated IS was responsible for the attack in revenge for the Egypt's airstrikes in Derna.

AFP, citing a doctor, put the death toll at 25.

The deadly development came after militants linked to the Islamic State (Isis) seized the university and other key buildings in the Libyan city of Sirte, the birthplace of former dictator Moammar Gaddafi.

Sirte residents said the militants also took over a radio station, Reuters reported.

Egypt launched airstrikes against IS targets in eastern Libya, after the jihadist group published a clip showing the beheading of 21 Egyptian Christians kidnapped in Sirte.