A sheriff's deputy opened a package on the third floor of the courthouse and several people immediately felt ill, officials said.
An Orange County hazardous materials team and the bomb squad responded around 2:30 p.m. and that area of the courthouse was blocked off, though the rest of the complex continued operations.
Court was not in session in that room at the time.
Authorities haven't determined yet what substance is involved.
Santa Ana- OCFA & OCSD on scene of a suspicious package, at Central Justice Center; 3 patients total. 1 Deputy transported. OCFA Haz-May & OCSD Bomb squad jointly investigating. More to follow... pic.twitter.com/K4wFPiJm7J— OCFA PIO (@OCFA_PIO) January 17, 2019
The Sheriff's Department said three civilians and one deputy were treated and were transported to a local hospital. They underwent decontamination before being transported. They were not considered to have life-threatening injuries.
There were no evacuations and the situation was described as "contained."
By around 5 p.m., officials said the initial investigation was complete and there was no additional threat to others at the courthouse.
The package was sent to a crime lab for further analysis.