Emergency workers received a call about 9 a.m. from the first-floor mail room of the Palm Beach County State Attorney's Office. A man and two women exposed to the powder suffered headaches and vomiting. A fourth person, a fire rescue worker, was taken to the hospital with them for a possible cardiac issue.
Alan Ortman, emergency manager for the city of West Palm Beach, told The Palm Beach Post News initial testing of the substance was "inconclusive." It was sent to an FBI lab for additional testing and could be identified within 24 hours, the newspaper said.
"Until that time we're going to keep the room where the powder was found sealed off," he said.
State Attorney Michael McAuliffe issued a statement confirming there was "an active, open investigation into the matter," but that there was no further information to release.