At least 17 people were killed after dozens of masked militants stormed a Yemeni government security compound yesterday, sparking a gun battle that continued into the night.

The Islamic State in Iraq and the Levent (Isil) terrorist group claimed responsibility for the attack, which began when a car laden with explosives detonated outside a building housing a police investigations unit in the government-held city of Aden early on Sunday morning.

About thirty gunmen then stormed into the unit and set free dozens of detainees, some of whom took up arms with their liberators, Yemeni authorities said.

There were reports that the militants had taken an unknown number of people hostage Sunday afternoon.

Yemeni authorities said at least 17 people had been killed by evening.

In its statement of responsibility issued late Sunday Isil said clashes were “still ongoing.

A civil war between the Yemen's Saudi-backed government and Shiite Huthi rebels, who are allied with Iran, broke out in March 2015.

The two-and-a-half year conflict has left much of the country devastated, with infrastructure destroyed and the population brought to the brink of famine.

Isil and al-Qaeda in the Arabian Peninsula (AQAP), a rival extremist group, have taken advantage of the chaos to unleashing attacks on both government targets and on the country’s Shiite population.