A suspicious letter forced the evacuation of Rep. Adam Smith's Kent district office Monday, Oct. 19. Smith represents parts of Bellevue in Washington's 9th Congressional District.

Staff opened the letter containing a powdery substance at the office at 6811 S. 204th St., Suite 360, the Issaquah Reporter first reported. The incident is part of a wave of suspicious mailings to congressional and election offices across the country, under FBI investigation.

"My staff has been safely evacuated, and I thank the Kent Police Department and the Renton Fire Department for their quick action," Smith said in an Oct. 19 post on X.

Hazmat units from Puget Sound Regional Fire Authority and Renton Regional Fire Authority were dispatched to the office at 2:45 p.m. that Monday, ABC News reported, citing Puget Sound Fire Division Chief Pat Pawlak.

No one was hurt, according to KING 5. The substance has not been identified.

Kent Police Chief Rafael Padilla said in an email to the Issaquah Reporter that his department had been asked to direct media requests to the FBI and U.S. Postal Inspection Service.

The FBI said in an Oct. 20 statement that it is investigating "a series of suspicious mailings sent to various addresses nationwide, including Secretary of State offices and their related election offices, and Congressional offices."

The agency said some letters contained "an unknown substance" and that investigators are working to identify those responsible.

Authorities have not confirmed whether the letter sent to Smith's office is connected to the broader wave. ABC News previously reported that law enforcement sources believe more than 100 letters apparently containing white powder may be circulating in the U.S. mail system.

The Kent incident follows similar mailings elsewhere in Washington state. An envelope containing white powder addressed to the Washington secretary of state's elections division was intercepted Oct. 15, the Spokesman-Review reported. Rep. Pramila Jayapal's Seattle office was evacuated Oct. 16 after a suspicious package was reported. Hazmat crews cleared that scene by about 3:30 p.m. that Friday, KING 5 reported.

Letters have reached congressional and election offices in at least 17 states, KATU reported. A similar wave struck election offices in six states in 2023; some of those letters contained traces of fentanyl, according to GBH, citing the Associated Press.

Smith is running for reelection on the Nov. 3 ballot against Republican challenger Doug Basler. The FBI and U.S. Postal Inspection Service said they are working to identify the sender or senders, and the powdery substance found at Smith's office remains unidentified.