(CNN) -- Drone strikes against militants in Yemen are intensifying as the U.S. Embassy there and in other Middle Eastern and African countries remain closed amid terrorism fears.
Six suspected U.S. drone strikes have been reported in the past two weeks alone. They have killed at least 29 people, according to a tally by Yemeni officials.
The latest strike happened early Thursday in central Yemen, where six people were killed, including four with links to al Qaeda, local security officials said.
Two civilians were among those killed in the strike in Mareb province, which targeted two vehicles, the officials said.
"Mareb was a previous stronghold for al Qaeda, and a number of members of the group still live in the province," a security official said.