Officials say the veteran threatened the agent with a knife.
Base commander Col. Larry Martin says at about 6 p.m. Wednesday, security was called to an altercation at a camping area inside MacDill.
The veteran described as a guest was arguing with another person. Martin says he sped off to one of the main entrances and got off his bike.
The FBI says he came at the agent with the knife. The FBI says the agent fired more than once, killing the man.
No one else was injured. The Air Force did not release the dead man's name or the name of the agent who is a liaison officer at the base.
