The gunman was among the two killed in the shooting at the Ft. Bliss Veterans Affairs clinic in El Paso in Texas, Major General Stephen M Twitty said.
Apart from the one victim and the gunman, all the hospital staff and patients were safe, said Twitty.
The FBI is investigating the case and further details were not made available by officials at a press conference at the post. There was also no clarity on whether the gunman killed himself or was killed by someone else.
The clinic, which is in a complex that also includes the William Beaumont Army Medical Centre, will remain closed tomorrow.