The late Sunday strike in the Markha district of the southern province of Shabwa also wounded another three suspected militants, the source told AFP.
It was the second drone strike in the province in as many days. On Saturday, a drone strike on a vehicle killed three militants in the village of Bijan.
Yemen has descended into chaos since a Shiite militia overran the capital Sanaa last September.
But President Barack Obama vowed in January not to let up in the US campaign against the jihadists' Yemen branch, Al-Qaeda in the Arabian Peninsula, which Washington regards as its most dangerous.
The port city and neighbouring provinces are largely controlled by troops and militia loyal to Hadi.
But Al-Qaeda has a strong presence in parts of the south, including Shabwa and Hadramawt province further east.
