Letters containing fentanyl sent to several US states’ election offices

Law enforcement officials in the US are searching for the people responsible for sending letters with suspicious substances sent to election offices in at least five states, acts some election officials described as “terrorism”.

Election offices in Georgia, Nevada, California, Oregon and Washington state all were sent the letters, four of which contained the deadly drug fentanyl, the Associated Press reported. Some of the letters were intercepted before they arrived. The FBI and United States Postal Service are investigating.

Related: Man accused of attacking Paul Pelosi absorbed conspiracy theories, trial hears

In Washington, election offices in four counties – Skagit, Spokane, Pierce and King, which includes Seattle – were evacuated as workers counted ballots from Tuesday’s election. Two of the letters tested positive for fentanyl. Steve Hobbs, Washington’s Democratic secretary of state, said the letters were “acts of terrorism to threaten our elections”.

In Georgia, a letter was sent to Fulton county, the target of many of Donald Trump’s baseless attacks. The Georgia secretary of state, Brad Raffensperger, a Republican, said at a Thursday news conference the letters were “domestic terrorism”.

The episode is the latest event to underscore the intensity of the threats and harassment election officials have faced since the 2020 election. Many of them are choosing to leave the profession, prompting concern that there will be a vacuum of experience in election offices that could be filled by novices or election skeptics, producing errors and delays in 2024.

Twelve per cent of election officials started their jobs after the 2020 election, and another 11% say they may leave before 2024, according to an April survey by the Brennan Center for Justice. Forty-five per cent of election officials say they fear for the safety of other election officials ahead of next year’s presidential election.

Linda Farmer, the county auditor in Pierce county, released an image of the letter her office received. It said “end elections now”, and contained the antifascist symbol, a pentagram and a progress flag, according to the AP. “Stop giving power to the right that they don’t have. We are in charge now and there is no more need for them,” the letter said.

Farmer told the Washington Post that a worker opening mail on Wednesday had discovered the letter and alerted her boss, prompting an evacuation of the facility. Farmer said she had later been told the substance contained in the letter was baking soda.

The Oregon secretary of state’s office also told the Washington Post that the election office in Lane county, which includes the city of Eugene, had received a letter, but that it would not affect completing the election.

The California secretary of state, Shirley Weber, a Democrat, confirmed that letters had been intercepted and an investigation was ongoing. “Federal and state authorities are investigating the incident, but there has been no confirmation that these envelopes contained any toxic substances,” she said in a statement.

Cisco Aguilar, Nevada’s Democratic secretary of state, also said in a statement his office was aware of letters sent to offices there.

Researchers have found that the risk of harm from accidentally touching fentanyl is low.

“This isn’t anything new – this is just a different tactic,” David Becker, an election administration expert at the Center for Election Innovation & Research, told the Washington Post. “It just represents the difficulty election officials have.”