LONG BEACH (CBS) — A workplace encounter turned deadly when a U.S. Immigration and Customs Enforcement agent turned a gun on his boss after he threatened disciplinary action at the Long Beach Federal Building Thursday evening.

Police officers were seen arriving at 5:50 p.m. Thursday to a report of shots fired on the 7th floor of the Glenn M. Anderson Federal Building.

Emergency dispatchers initially reported that one person was shot behind closed doors. They later reported that an ICE agent fired upon another agent in the stomach.

The victim was transported to St. Mary Medical Center and was listed in stable condition, ICE reported.

The agent sustained multiple wounds to multiple parts of his body, according to Trauma Director James Murray. He did not detail where he was shot. The victim’s vital signs were “good for now”, said Murray, adding that he had ongoing bleeding but that it wasn’t a cause for concern. As of 10:30 p.m. the agent was still in surgery.

During a press conference held by the FBI and ICE, officials said the incident began when an ICE supervisor called in an agent to discuss disciplinary action. The agent responded by shooting his superior. Another employee intervened and shot the gunman, who died at the scene.

Authorities have not disclosed who shot the gunman.

U.S. Immigration and Customs Enforcement released the following statement Thursday night:

“At approximately 5:30 (Pacific) this afternoon, two agents with U.S. Immigration and Customs Enforcement’s (ICE) Homeland Security Investigations (HSI) were shot inside the agency’s offices at the federal building in Long Beach. One of the agents died at the scene. The second agent was transported to a local hospital where he is listed in stable condition. The names of the agents are not being released pending notification of the next of kin. The shooting is being investigated by HSI’s Office of Professional Responsibility, the Long Beach Police Department and the FBI.”