Police officers, firefighters and an ambulance crew responded last month to a BART station at around 2 a.m. to deal with an unsteady station agent who said he was having a diabetic attack but turned out to be extremely drunk, according to public records and agency sources familiar with the matter.

Though BART police officers had to step in and close up the station in downtown Concord after the Dec. 23 incident, officials refused to comment on what happened, citing the privacy of personnel matters. It’s not clear where the agent allegedly consumed alcohol, how he got to the station that night, and how authorities were alerted that he was having trouble with his duties.

The agent may be disciplined by BART but does not face criminal consequences, agency sources said. Under California law, those suspected of “intoxication only” are typically released without charges. After release, “the arrest shall not be deemed an arrest, but a detention only,” the law states.

According to an incident report from the Contra Costa County Fire Protection District, a call came in at 2:23 a.m. about a 50-year-old man having “diabetic” problems. The district sent a fire engine and ambulance, which pulled into the station about 2:30 a.m. At 2:47 a.m., the ambulance crew released the patient.

Concord Police Lt. Kristen Thoms told The Chronicle that officers assisted BART police with an arrest at the Concord station at about that time. One BART source familiar with the case said police determined through a breathalyzer test that the agent had a blood alcohol concentration more than three times the legal limit for driving in California. The Chronicle is not naming the agent because he is not accused of a crime.

Rachel Swan is a San Francisco Chronicle staff writer. Email: rswan@sfchronicle.com Twitter: @rachelswan