Federal and state authorities are investigating whether the envelopes contain toxic substances, but there has been no confirmation yet that they do, Weber said. Envelopes containing suspicious substances including fentanyl have also been sent to election offices in Georgia, Oregon and Washington, Weber said.

The state is urging local election offices to take precautions before handling mail that arrives at their facilities, she said.

Also on Thursday, Georgia state secretary Brad Raffensperger told a press conference said Georgia had been alerted that suspicious envelopes had been sent to election offices in the state, local media reported.

ABC News reported the Texas public safety department and the FBI were investigating a letter containing an unknown substance sent to the state attorney-general’s office, citing law enforcement.

The scares come days after voting in a number of state elections and less than 10 weeks before the Iowa presidential nominating contest kicks off the 2024 presidential campaign in earnest.

The US justice department did not immediately respond to a request for comment from Reuters.