FRANKFURT, Germany — The suspect in the slaying of two U.S. airmen at the Frankfurt airport confessed to targeting members of the American military, a top security official said today, in a case that German officials are treating as a possible act of Islamic terrorism.

German federal prosecutors took over the investigation into Wednesday’s shooting, which also injured two airmen, one of them critically. They are working together with U.S. authorities.

Hesse state Interior Minister Boris Rhein told reporters in Wiesbaden that the suspect, identified as a 21-year-old ethnic Albanian from Kosovo, was apparently radicalized over the last few weeks and acted alone, the DAPD news agency reported.

The airmen were based in Britain, a U.S. Air Force spokesman for the Lakenheath airfield in eastern England. They were bound to Ramstein Air Base from where they were to have been deployed to support an overseas operation, the U.S. military said, without elaborating.

The U.S. has some 50,000 troops stationed in Germany.