The blast happened in the Balili mosque near a police academy in Sanaa, which is controlled by the Huthi Shiite insurgents, according to witnesses, some of whom reported dead and wounded.
The Yemeni capital has been shaken by a string of bombings of Shiite mosques in recent months claimed by the Islamic State jihadist group.
The radical Sunni Muslim group considers Shiites to be heretics and has also claimed bombings of mosques in Kuwait and Saudi Arabia.
The Iran-backed Huthi rebels have seized several regions of Yemen including Sanaa which they overran a year ago.
The Islamic State group and the Yemen-based branch of its jihadist rival Al-Qaeda have exploited the turmoil to boost their activities in the impoverished country.