An unknown number of U.S. special forces were killed or wounded in Afghanistan and a medical helicopter went down while trying to help them, NBC reported on Tuesday, citing unidentified U.S. officials.

Early reports indicate that one American service member died and two others were wounded amid the incident in southern Afghanistan, NBC News reported on Tuesday, citing a senior U.S. defense official.  

It was unclear if the helicopter was brought down deliberately, it reported. However, an Army spokesman said the helicopter landed safely in Helmand Province.