Earlier in the day, the Yemen security officials have said that they believed Al-Qaeda was behind the suicide attack.
Following the bombing, gunmen attacked the building of the Criminal Investigation Department (CID), the source added on condition of anonymity because he was unauthorized to speak to media. The blast was heard across the city and a plume of smoke could be seen from miles away.
Islamic State militants claimed responsibility for the assault, without providing evidence.
A suicide vehicle bomber blew himself up at a security checkpoint in the southern Yemeni port city of Aden on Sunday, killing 15 people and wounding at least 20, residents and a security official said.
Clashes erupted in the area immediately afterward, witnesses reported. "Elite soldiers are trying to kick the terrorists out of the security buildings". The attackers even took some of the police detectives hostages inside the building.
Islamic State (IS, formerly ISIS/ISIL) has claimed responsibility for the attack.
The government of Yemen was forced to move to Aden after the capital Sanaa was seized by Houthi rebels.
While southern Yemen has always been the target of the a drone war by the United States, which classifies AQAP as the radical network's most unsafe branch, Washington appears to have recently turned its aim towards IS as well. Al-Qaida and other Islamist groups have used the chaos in the country to expand its influence.
IS and its extremist rival al-Qaeda in the Arabian Peninsular [AQAP] have taken advantage of the war between Yemen's Saudi-backed government and the country's Houthi rebels, who are allied with Iran, to bolster their presence across much of the south.
United Nations statistics show more than 10,000 people, a lot of them civilians, have been killed since the coalition intervened in the Yemeni civil war that also displaced around three million.
Long the poorest country in the Arab world, Yemen now stands steps away from an official declaration of starvation, as war, displacement, and port and airport blockades leave Yemenis struggling to secure food.