State Health Department spokesman Donn Moyer says the test was specifically for plague. Tests for anthrax and plague conducted Tuesday also were negative.

The department is still conducting a couple of other tests, including one for botulism.

Meanwhile, postal employees were back at work at the mail processing center in Tacoma where the suspicious powder forced an evacuation and closure of the building Tuesday.

No sign of toxic agents were found in a granular substance at a similar mail-sorting operation in Tukwila, officials said.

Biotoxin Found At Postal Facility

None of the 94 Tacoma workers who were evacuated after the powder was discovered about 12:45 a.m. Tuesday showed any symptoms of botulism or other potential bioterrorist ailments, and the mail-sorting operation was reopened late Tuesday afternoon, officials said.

Four people who were close to the powder were decontaminated as a precaution, then were checked at a hospital and released.

Federal officials said powder samples would be sent to the federal Centers for Disease Control and Prevention for review.