A shooting in a federal building near a Los Angeles left one immigration officer dead and another wounded in what appears to be the result of a dispute between an agent and his supervisor.

At the Glenn M. Anderson Federal Building in Long Beach, Calif., the gunman, a special agent of Immigration and Customs Enforcement allegedly had a dispute with his supervisor shortly before 6 p.m. The supervisor allegedly threatened disciplinary action, according to CBS. The agent pulled out his weapon and shot his supervisor, wounding him.

A third agent, seeing the commotion, reacted quickly firing at the agent, killing him. The supervisor was taken to a St. Mary Medical Center by a Long Beach Fire Department ambulance. He is in stable condition, reported the L.A. Times.

James Murray, St. Mary's Trauma Director, said the supervisor received several gunshot wounds, but that his vital signs were good for now, reported CBS.

The names of the three individuals involved in the incident have not been released.

At this time we believe this was an isolated incident and that the shooter acted alone, Steven Martinez, assistant director in charge of the Los Angeles FBI office, told reporters at the scene, according to the L.A. Times.

Claude Arnold, special agent in charge of the ICE office in Los Angeles, did not provide any details of the shooting because the incident is currently being investigated.

Obviously, there's still many questions that remain to be answered, Arnold said. Our hearts go out to all those who have been affected.

According to a press release, the shooting is currently being investigated by Long Beach Police Department, the FBI and Homeland Security's Office of Professional Responsibility.