At least 11 people have been killed after a suicide bomber rammed an explosives-laden car into a military police base in al-Mukalla, in southeast Yemen.
Witnesses in the provincial capital of Hadramawt reported an ambulance ferrying casualties to a city hospital on Sunday.
The blast came as government forces hunted al-Qaeda fighters in the south.
In an earlier attack on Sunday, three fighters were killed after they tried to attack a security checkpoint in the Yemeni capital, the interior ministry said the shootings were the second such incident close to the presidential palace in Sanaa in as many days.
A civillian was also killed during the gunfight which erupted at dawn.
The attack in Sanaa appeared to be retaliation for the army offensive against al-Qaeda that has ousted many fighters from bastions in south Yemen which they first seized during mass unrest in 2011.
Five guards were killed on Friday in clashes that broke out after gunmen attacked the checkpoint outside the palace in Sanaa which the president, who was not there at the time, only uses for meetings.
Sanaa has been on alert for days, and tensions rose after the army said troops had entered Azzan, a rebel stronghold in southern Shabwa province, prompting the United States to close its embassy on Thursday.
Friday's attack on the palace came hours after the defence minister, who has vowed to crush fighters active in Yemen, survived an ambush by suspected al-Qaeda fighters in the south.
Yemen's army says its offensive against al-Qaeda in the Arabian Peninsula (AQAP) strongholds in the contiguous provinces of Shabwa, Abyan and Baida has inflicted heavy losses on the fighters.
AQAP is considered by Washington as the most dangerous affiliate of al-Qaeda and has been linked to failed plots in the US.
Western powers are concerned that AQAP could use Yemen as a springboard for future international attacks.