In a statement, the al Shabaab group said the attack, launched at dawn, was continuing hours later and said their fighters were engaging U.S. troops in close-quarters combat.
"Seven aircraft and three military vehicles were destroyed in the attack," said the statement, which included photos of aircraft ablaze and an al Shabaab militant standing nearby.
In a tweet, the U.S. Africa Command confirmed an attack on the Manda Bay Airfield had occurred. It said it was monitoring the situation and would provide an update "as facts and details emerge."