An envelope with the same markings and white powder found to be harmless in three other cases has been found on campus at the University of California, Irvine.
University spokesman Tom Vasich said Tuesday the return address on all four envelopes is in Idaho. Each contained a letter with the words "Black Death."
Vasich says the assistant dean of biological sciences and a computer sciences counselor opened the letters addressed to them Tuesday, prompting the evacuation of two offices in the natural sciences and computer sciences buildings.
Two other buildings were evacuated Monday when two professors opened similar letters. The substance inside has not been identified.
Vasich says the only thing the four targeted employees have in common is that they are women.
THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
IRVINE, Calif. (AP) _ Authorities have determined that white powder sent to three people at the University of California, Irvine is not hazardous.
Two professors received the powder Monday in envelopes with the words "Black Death" written on them. A third envelope was received Tuesday in the computer sciences building. It wasn't immediately clear who was the recipient.
University spokeswoman Cathy Lawhon said Tuesday the substance hasn't been identified, but tests show it is harmless.
Parts of a social sciences building, an engineering tower and the computer sciences building were evacuated after the envelopes were received.
University officials sent an e-mail alert to students, faculty and employees, warning them to be cautious of opening suspicious mail.