The Huthi rebels, who are also facing Saudi-led air strikes, were travelling in three vehicles from Lahj province towards Aden, the southern stronghold of embattled President Abedrabbo Mansour Hadi, when they were ambushed.
The attack took place just 15 kilometres north of Aden, where tensions were high on Friday as the rebels clashed with the "popular committees" -- an anti-Huthi militia controlling parts of the city, security officials and residents said.
At least eight people were killed in clashes around Aden airport, where the Shiite militiamen were deployed on the runway, security and medical sources said.
Meanwhile, dozens of youths looted arms depots abandoned by troops in the Khormaksar neighbourhood, security officials told AFP.