Two U.S. Navy pilots were shot down Sunday over the Red Sea in an apparent “friendly fire” incident, the U.S military said, marking the most serious incident to threaten troops in over a year of America targeting Yemen’s Houthi rebels.

The guided missile cruiser USS Gettysburg, part of a carrier strike group in the region, mistakenly fired on the jet, U.S. Central Command said in a statement.

An F/A-18 fighter jet was "mistakenly fired on" by the guided missile cruiser USS Gettysburg, authorities said.