Three people are dead and one person is injured, said the employee, who wished not to be named. Michigan State Police confirmed the shooting occurred around 2:30 p.m. Monday.
Two of the people dead are court bailiffs. The other person dead is the shooter, the employee told the TV station.
State police have not confirmed those numbers nor the status of the shooter.
Michigan Gov. Rick Snyder tweeted that police have secured the scene at the courthouse and have begun their investigation.
Please join me in praying for those affected. We will share more information here from MSP as it becomes available.— Governor Rick Snyder (@onetoughnerd) July 11, 2016
MSP has secured the scene at the Berrien County courthouse and started its investigation into the shooting that occurred this afternoon.— Governor Rick Snyder (@onetoughnerd) July 11, 2016
State police Lt. Mike Shaw says the department is in gathering information but could not confirm whether there are any casualties.
St. Joseph is located in far southwestern Michigan's Berrien County, which borders Indiana.
The Associated Press contributed to this report.