A suicide bomber blew up a vehicle at an elite Republican Guard camp southwest of the Yemeni capital on Saturday, days after Al-Qaeda claimed a similar attack that killed 26 soldiers, military sources said.
There were "casualties" in the blast at the base in Bayda, 170 kilometres (105 miles) from Sanaa, the sources added.
Witnesses said the bombing devastated the three-storey building.
The explosion was followed by an exchange of fire between gunmen and Republican Guard troops, who are led by Ahmed Saleh, son of veteran strongman Ali Abdullah Saleh, who formally stepped down less than a week ago.
Bayda borders Abyan province, an Al-Qaeda stronghold in the south.
On Wednesday, the jihadists' Yemen franchise, Al-Qaeda in the Arabian Peninsula (AQAP), claimed responsibility for a suicide attack on a presidential palace in Hadramawt province in the southeast that killed 26 Republican Guards last week.
That attack came as President Abdrabuh Mansur Hadi, the first new president in Sanaa since 1978, took the oath of office as Saleh's successor.
AQAP said that the bombing of the palace in the Hadramawt provincial capital Mukalla was "a clear message to the US ambassador" after alleged remarks he made "about restructuring the Yemeni army."
"This is a message to say that the US project in Yemen will not succeed and that our operations will target this project and its tools wherever they may be," AQAP said.
In an address to the nation straight after being sworn in to succeed Saleh, Hadi vowed to press the fight against Al-Qaeda and restore security across his impoverished nation.
"It is a patriotic and religious duty to continue the battle against Al-Qaeda," the new president said.
"If we don't restore security, the only outcome will be chaos."
Yemen is the ancestral homeland of slain jihadist leader Osama bin Laden.