Casualties feared after attacker destroys three-storey Republican Guard building in Bayda, southwest of Sanaa.
A suicide car bombing is reported to have targeted Republican Guard troops camp southwest of the Yemeni capital, just days after al-Qaeda claimed a similar attack that killed 26 soldiers.
There were "casualties" in Saturday's blast at the base in Bayda, 170km from Sanaa, military sources said.
Witnesses said the bombing devastated the three-storey building.
The explosion was followed by an exchange of fire between armed men and Republican Guard troops, who are led by Ahmed Saleh, son of the former president, Ali Abdullah Saleh, who formally stepped down less than a week ago.
Bayda borders Abyan province, an al-Qaeda stronghold in the south.
Al-Qaeda in the Arabian Peninsula (AQAP) claimed responsibility on Wednesday for a suicide attack on a presidential palace in Hadramawt province, in the southeast, that killed 26 Republican Guard soldiers last week.
That attack came as Abd-Rabbu Mansour 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 Hadramawt's 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 the Arabian Peninsula country.
"It is a patriotic and religious duty to continue the battle against al-Qaeda," Hadi said.
"If we don't restore security, the only outcome will be chaos."