No injuries have been reported and the building has been deemed safe.
According to the CHP, the call originally came in after an employee reportedly saw a person with a gun in the building around 6:41 a.m. The CHP responded and locked the building down for about two hours, thoroughly sweeping the building and checking cameras.
It was determined the person with the firearm they were originally looking for was no longer on site, so the lockdown was lifted.
The Caltrans building is closed for the rest of the day.
The CHP says the person with a firearm in the building has been identified and was not an employee.