A suicide bomber attacked young men queueing up to enlist in the Yemeni army in the southern port city of Aden on Monday, killing at least 20, a military official said.
The bomber detonated an explosives belt after joining the queue at the recruitment centre near the Badr base in the Khormaksar district of the city, where the government of President Abedrabbo Mansour Hadi is based.
A second explosion went off inside the base afterwards, the official said. He had no immediate word on any casualties from that blast.
Al-Qaeda and its jihadist rival, the Islamic State group, have claimed responsibility for a spate of attacks on government forces who drove Huthi Shiite rebels out of the city in July with support from a Saudi-led coalition.
The two jihadist groups exploited the power vacuum created by the conflict to expand their presence in the south and southeast.
But over the past two months, government and coalition forces have hit back, driving the jihadists out of Aden, as well as the Hadramawt provincial capital Mukalla, which they had controlled for a year.