Observed by: Mr. Alaa Isam
The gunmen, suspected of being from a local al Qaeda unit, ambushed an army-escorted postal truck carrying cash in a town in the southern province of Hadramout, said the official.
Militant attacks have been frequent in the south, where Yemen is trying to quell a resurgent wing of al Qaeda and growing separatist militancy.
Al Qaeda's Yemen-based wing has stepped up attacks on Western and regional targets in the poor Arabian peninsula state, a neighbour of oil giant Saudi Arabia.
Yemen is also trying to maintain a truce with Shi'ite rebels in the north of the country, which is a focus of Western security concerns after two U.S.-bound parcel bombs were intercepted in Britain and Dubai in October, a plot claimed by al Qaeda's local wing.
(Reporting by Mohammed Mokhashaf; Writing by Firouz Sedarat; Editing by Alastair Macdonald)