The discovery of an unidentified powder prompted authorities to evacuate the administration building at a special education school in Brewer on Tuesday afternoon, while police closed an Interstate 95 rest stop in Hampden after workers found a grayish-white powder on the floor inside the building there.

In both instances, precautionary decontamination procedures were put into place, although it appears neither case involved anthrax.

At Brewer’s Stillwater Academy, run by Community Health and Counseling Services, an employee discovered the powder in a sales catalog about 1 p.m.

Though no students are believed to have come in contact with the powder, the school’s administration building was locked down and six staff members who were inside at the time were quarantined briefly and then taken to the Brewer Auditorium for decontamination, which largely involved showering with antibacterial soap, according to Brewer Police Department Detective Sgt. Perry Antone.

Antone said Tuesday that while police had no reason to believe the powder contained anthrax spores, police and fire personnel contacted the Maine Emergency Management Agency and as a precaution followed the Centers for Disease Control and Prevention protocol for handling unidentified substances that might contain anthrax.

“It’s one of those better safe than sorry deals,” Antone said. If the substance is found to be anthrax-free, Stillwater Academy will go back to business as usual. If anthrax were found, however, the Federal Bureau of Investigation would be called in, Antone said.

The powder was collected and then packaged securely by firefighters wearing breathing equipment. Police Capt. Dan Green hand-delivered the package to the State Environmental and Health Testing Laboratory in Augusta.

Police Chief Steven Barker said Tuesday night that the amount of white powder was so small lab officials said they would have to grow cultures before determining the substance’s contents. That is expected to take two days. In the meantime, the administration building will remain closed.

According to Lt. Dennis Tinkham of the Brewer Fire Department, a staff member at the school was leafing through a sales catalog received in the mail when some white powder fell out and onto an article of clothing. The worker removed the article of clothing, called emergency responders and went home to shower. Six others who were in the office at the time but who were believed to have avoided contact with the substance were decontaminated at the auditorium, which in turn was cleaned.

Tinkham recommended that people who come in contact with suspicious substances call their local police or fire departments. If possible, they should remain at the scene because that makes it easier for emergency personnel to confine the substances and prevent others from being exposed.

On the interstate, state troopers and Hampden police blocked off the southbound entrance to the rest stop for more than two hours after a grayish-white powder was found on the floor throughout the building and outside where footprints formed by the substance were found, said Hampden Deputy Fire Chief Michael Andersen. Authorities took a sample, sealed it in a bag, a sterile jar and then in another bag in preparation for being brought to state laboratories in Augusta for examination. Andersen said they might find out sometime today whether the substance contained anthrax.

Two workers who had left the southbound rest stop and showed up at the northbound rest stop were sent back and had the soles of their shoes decontaminated, he said. The building at the southbound rest stop has been sealed and the access road closed pending identification of the substance.

Less than a mile down the interstate, authorities found more powder on the road itself and for several minutes shut down the southbound lanes. Andersen said as was the case at the rest stop, he put on protective gear and examined the materials. In the powder he found wallboard paper, leading him to conclude that a piece of wallboard had fallen onto the highway and crumbled.