Suspicious mail containing white powder sent to election offices in at least 16 states

JEFFERSON CITY, Mo. -- The FBI and Postal Service are investigating suspicious mail containing a white powder substance that was sent to election offices in at least 16 states this week, according to an ABC News canvass of the country.

None of the mail has been deemed hazardous so far - and in one case, the substance was determined to be flour - but the scare prompted evacuations in some locations.

Election offices in New York, Tennessee, Wyoming, Kentucky, Oklahoma, Iowa, Nebraska, Missouri, Kansas, Indiana, Massachusetts, and Colorado received the suspicious packages. Similar suspicious mail was addressed to offices in additional states - Arizona, Georgia, Connecticut and Maryland among them - but investigators intercepted them before they reached their destination.

The FBI and U.S. Postal Inspection Service said in a statement Tuesday that they were investigating letters containing white powdery substances. A law enforcement source said at this point none of the packages were believed to be hazardous.

"We are also working with our partners to determine how many letters were sent, the individual or individuals responsible for the letters, and the motive behind the letters," the statement read.

At least some of the packages were signed by the "United States Traitor Elimination Army," according to a copy of a letter sent to members of the Elections Infrastructure Information Sharing and Analysis Center obtained by ABC News.

Election offices office in Kansas and Wyoming were evacuated on Monday, officials said, and the ventilation system in the Missouri secretary of state's office in Jefferson City was briefly shut off as a precaution. The North Carolina Board of Elections did not receive any packages with white powder, but an official there told ABC News they are putting in place new safety precautions in light of the incidents in other states.

This latest incident marks the second time in the past year that suspicious mailings containing a white powdery substance were sent to election offices. Last November, similar envelopes were sent to elections offices in five states -- four of which tested positive for fentanyl, the FBI said at the time.

In the intervening months, several offices have taken steps to train staff on how to handle poisonous material sent in the mail. In Milwaukee, for example, election workers recently received training on how to administer Narcan.

The National Association of Secretaries of State released a statement urging an end to the "threatening and intimidating actions towards election officials" during recent election cycles.

"This must stop, period," the statement read. "Our democracy has no place for political violence, threats or intimidation of any kind."