One man has been wounded but is in custody at Joint Base San Antonio Fort Sam Houston.
Officials at the base say the man tried to force his way past the gate about 12:30 Saturday afternoon but ran when guards tried to apprehend him.
One of the guards fired a gun on the suspect, injuring him just before he was taken into custody.
Base officials have not said how bad the man's injuries might be.
The suspect was taken to a hospital where he's expected to be questioned about the incident later.
No other injuries were reported.