A security official says three Yemeni soldiers were killed when assailants opened fire on their checkpoint in a southern port city.
The official said a police vehicle was set on fire on the Friday attack on a checkpoint separating two districts in Aden.
Another security official says investigators suspect the attackers were driving a vehicle loaded with weapons.
The officials spoke on condition of anonymity because they were not authorized to brief the media.
Aden is close to parts of southern Yemen where militants, taking advantage of a year of political turmoil in the southern Arabian country, have been seizing control of territory.