LONG BEACH, Calif. - An immigration agent shot and injured another agent Thursday and was then killed by a third colleague in a federal building in Long Beach, the FBI said.

The shooting occurred at about 5:30 p.m., said FBI Special Agent Steven Martinez.

There were conflicting early reports about the number of people shot, with local authorities saying two were dead and one wounded, while ICE said one was dead and one wounded.

Martinez characterized the incident as a case of workplace violence involving two federal agents. He says one agent fired several rounds at another agent, wounding him. At that point, another agent intervened and additional rounds were fired, resulting in the death of the shooter.

The wounded agent is hospitalized in stable condition, ICE Special Agent in Charge Claude Arnold.

"At times like this words honestly seem inadequate. When something like this happens in our offices, it's incomprehensible, Arnold said.

Names of the agents involved were not released pending notification of next of kin.

In addition to ICE, the nine-story federal building also houses the Internal Revenue Service and the U.S. Probation and Parole Office.