Police in Huntsville, Alabama, report a man opened fire at a temporary employment agency, Labor Ready, early Tuesday.
A hospital spokesman said three people died at the scene. One died later at the hospital. One other was wounded.
"The next thing I knew is I heard a shot and he had shot the man in the head. And the man hit the floor," said Patricia Johnson, an eyewitness who escaped injury. "And I looked up and he was pointing a gun at me and the gun clicked. And that's the last thing I know."
Police officials said the shootings followed an argument at the front counter of the employment agency.