The rebels were preparing for a patrol on the highway linking Marib to the capital Sanaa when an Al Qaeda member carried the attack against them, sources said, adding that about 20 people were wounded in the explosion.
The Al Qaeda in the Arabian Peninsula (AQAP) claimed the attack in a statement posted on its website and vowed more attacks against the Houthi group in the future.
Dozens of people were killed in sporadic clashes between the Houthi rebels and Al Qaeda militants in Yemen's southern regions in the past few weeks, after the Houthi group launched military offensive in Sanaa and eventually took over the capital.
The Houthis, based in the country's far north, tightened their control in Sanaa and started expanding in the southern regions after signing a ceasefire deal with the government last week.
However, security in the Arab country deteriorated as clashes paralysed the central government.
On Saturday night, the US embassy in Sanaa was attacked by a rocket which wounded five security guards. The AQAP claimed responsibility for the attack.
The US administration Thursday ordered a reduced diplomatic presence in Yemen and warned citizens against travel to the Arab country, citing "changing" and "unpredictable" security situation there.