The envelope arrived through the state mail processing facility and was opened by a clerk on the tower’s seventh floor, which includes offices for the governor, treasurer and secretary of state, along with other state agencies. Employees contacted law enforcement, and officials isolated the substance and anyone who might have been exposed, according to the Arizona Department of Public Safety. No injuries were reported.

Secretary of State Adrian Fontes said the material was not harmful, but officials had not yet determined what it was. Testing was underway, and investigators temporarily quarantined the mail processing facility as they traced the envelope’s path.

The FBI is leading the investigation. The bureau has said it is examining suspicious mailings sent to addresses nationwide, including offices of secretaries of state and related election offices. Fontes said investigators may consider whether Arizona’s incident is connected to other reports.

The scare comes about three weeks before Election Day, amid reports of similar mailings to election offices in multiple states. Offices in Louisiana and Oklahoma were evacuated this week; Ohio officials said a package intended for their office was intercepted by the Postal Service. Wisconsin officials also reported that testing found powder sent to its elections commission was not hazardous.

The FBI and U.S. Postal Inspection Service said they are working with law enforcement partners to investigate the letters and identify those responsible. Fontes urged county and other election officials in Arizona to remain alert, saying threats aimed at election workers could be intended to disrupt voting or undermine public confidence.

Gov. Katie Hobbs, who was not in the tower during the incident, thanked first responders and said those responsible for threatening or intimidating election officials should be held accountable.