A bomb planted on a military bus has killed two in the latest string of violence hitting the Yemeni capital.
Yemeni officials said the Tuesday morning blast in Sanaa also wounded at least 10 soldiers. It hit as the bus was passing through the Dar Silm district, taking officers and troops to work.
The officials, who have spoken on the condition of anonymity, say they are investigating whether the explosion was caused by a bomb hidden on the bus, a roadside device or a suicide bomber.
The renewed violence that has targeted Yemeni military comes as the government struggles to end fighting between Shia Houthis and powerful tribesmen in the north, and seeks to turn the Arab republic into a federation.
The explosion was the latest in a series of security incidents to hit Yemen in less than a week, and a day after thousands of Shia Houthis rallied against government in the capital.
Two Westerners have been kidnapped since Friday and three explosions near the French embassy, the defence ministry and the central bank, shook the capital late on Sunday.
Attacks on military personnel are usually blamed on al-Qaeda, whose Yemen branch is one of the most most active branches.
Yemen has been hit by turmoil since mass protests in 2011 eventually forced out long-serving President Ali Abdullah Saleh.
The country, which neighbours Saudi Arabia, is wrestling with instability, internal conflicts and poor governance.
Fighting for autonomy
Scores of people have been killed in a month of combat between Houthi rebels and members of the powerful Hashid tribe that erupted on January 5.
Meanwhile, President Abdrabuh Mansur Hadi sent Sanaa governor Abdulqader Hilal to the northern province of Amran to try and broker a ceasefire and end bloody clashes there.
On his Facebook page, Hilal said both sides had welcomed his mediation efforts and agreed to sign a deal on a "ceasefire, opening roads, and the withdrawal of fighters".
Tribal sources said fighting that raged last week, killing an estimated 150 people and wounding 400, subsided on Monday to allow mediation efforts.
The Houthi rebels have been advancing from their stronghold in the mountains of the far north to other areas near the capital to expand their hoped-for autonomous area in a promised federal Yemen, political sources say.
Hadi has pledged that Yemen will adopt a federal constitution in a bid to address local grievances that have fuelled violence across the Arab world's poorest country.
But at a ceremony last month to mark the conclusion of a troubled 10-month national dialogue, he postponed any decision on the thorny issue of how many components it will have, promising that a special commission will decide.
The prospect of a federal Yemen was originally mooted as a way to address grievances of the formerly independent south, where secessionist violence has also been rising.