Four people became ill after a sheriff's deputy opened a small cardboard box found in a courtroom in Santa Ana on Thursday, officials said.
All the patients were subsequently taken to a hospital for further evaluation, but their symptoms were not life-threatening, Orange County Fire Authority Capt. Larry Kurtz said.
A bomb squad and hazardous material team responded after the incident was first reported on the third floor of the Central Justice Center on Civic Center Drive in Santa Ana around 2:30 p.m., according to Carrie Braun, a public information officer for the O.C. Sheriff's Department.
Braun said the deputy, a male in his 50s, was in medical distress and felt the need to report the situation. The other three affected were all court employees.
The deputy and one other were taken to the hospital immediately, while the remaining two patients were "decontaminated" before being transported, Kurtz said.
Investigators were still trying to determine whether the package was mailed to the courthouse or left there by someone. Court was not in session when it was discovered, officials said.
Authorities were also awaiting the result of forensic analysis to determine what it contained.
"Unfortunately, substances like this don’t come with labels," Kurtz said.
Hazmat crews determined there was no further threat to the courthouse or public, but the investigation was ongoing.
No further details were immediately available.