There were "casualties" in the blast at the base in Bayda, 170 kilometres (105 miles) from Sanaa, the sources added, without giving any immediate breakdown.
Witnesses said the bombing devastated the three-storey building.
The explosion hit at 6:00 am (0300 GMT) and was probably carried out by multiple assailants, a military official said.
The blast 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.