The Arizona Department of Public Safety, its hazardous materials team and the FBI are investigating, according to Hobbs’ office. Secretary of State’s Office employees called law enforcement and hazmat responders, isolated the material and people who may have been exposed, and restricted access to the floor. Officials had not identified the substance.

Secretary of State Adrian Fontes said the incident underscored the security risks facing election administrators. His office, he said, would not be deterred from serving voters and remained on high alert as the Nov. 3 general election nears.

The FBI said it and the U.S. Postal Inspection Service are investigating a series of suspicious mailings sent to addresses across the country, including state secretaries of state and election offices. Some letters contained an unknown substance, the FBI said, and investigators are working to identify whoever sent them.

Election offices in Louisiana and Oklahoma were evacuated earlier this week after receiving packages with powdery material. Ohio’s secretary of state said a package containing white powder addressed to that office was intercepted by the Postal Service. Other states, from Idaho to Florida, also reported receiving or intercepting suspicious mail, while tests on a letter sent to Wisconsin’s elections commission found its powder was not hazardous.

The latest reports follow a 2023 series of letters containing white powder sent to election offices in six states; some tested positive for traces of fentanyl. The current incidents come less than three weeks before Arizona voters head to the polls.