Washington Post quoted U.S. Central Command statement.
Inquired as to whether the crash included another exceptional powers strike, Central Command revealed to The Associated Press that "this was a standard preparing occasion particularly for USA military work force".
A U.S. military helicopter crashed during a training exercise off the coast of Yemen Friday, U.S. Central Command reported Saturday.
Friday's crash comes just two days after a visit to the Saudi-Yemen border by Gen. Joseph Votel, who oversees the US military throughout the Middle East. Children were also among the casualties.
Yemen, located on the southern end of the Arabian Peninsula, is engulfed in the years-long civil war.
The crash on Friday was one of a number of aviation mishaps involving United States military aircraft in recent months, and the third involving a Black Hawk helicopter.
Several thousand USA sailors and Marines also routinely operate in the region as part of a naval amphibious ready group.
Five other US service members who were aboard the aircraft have been rescued, Central Command said.
The U.S. troops are limited to advisory and intelligence work, but they could be drawn into conflict in self-defense, Navy Capt. Jeff Davis, a Pentagon spokesman, said earlier this month.
Asked if the crash involved another special operations raid, Central Command told The Associated Press that "this was a routine training event specifically for USA military personnel".
Also this month, a Marine Corps MV-22 Osprey crashed off the coast of Australia.