Yemeni security and medical officials say a suicide bomber has killed two pro-government fighters at a checkpoint in the southern port city of Aden.

The officials say the attack was in Aden's Mansoura neighborhood.

It followed the Sunday storming of a supermarket by Islamic militants, who fired shots into the air and briefly took hostages, according to security officials and witnesses.

Witnesses said the attackers warned supermarket employees against the mingling of men and women and demanded that female employees cover their faces.

Following a large battle over Aden between Shiite rebels, known as Houthis, and pro-government forces who pushed the Houthis out of Aden in July, al-Qaida appears to have taken advantage of the security vacuum as pro-government forces moved on to challenge the Houthis elsewhere in southern Yemen.