In a statement by their military media unit, the rebels, known as Houthis, say that a child was killed in today's attack that badly damaged a department of records building and wounding some 58 people.
Security officials and witnesses said many of the dead were civilians, speaking on condition of anonymity because they feared retribution.
The Saudi-led coalition has been at war with the northern-based rebels, who are from the Zaidi sect of Shiite Islam, since March 2015 to reinstate the government of President Abed Rabbo Mansour Hadi.