BERLIN (Reuters) - A firefight broke out between Afghan security forces and unknown assailants at the North Gate of Kabul airport on Monday, the German Bundeswehr said on Twitter.

       One Afghan security force member was killed and three others were injured in the battle, which also involved U.S. and German forces, the Bundeswehr said.

       All Bundeswehr soldiers remained uninjured, it said.

       (Reporting by Caroline Copley; Editing by Tom Hogue)