A California congressman’s office has become the latest target in a nationwide spate of suspicious mailings after a staffer opened an envelope containing white powder.

Democratic Rep. Jimmy Panetta confirmed the incident in a statement posted to social media on Friday, saying the envelope was delivered to his Santa Cruz district office during a staff member’s usual morning routine responding to constituents.

“Upon realizing that there was powder in the envelope, she immediately put the envelope in the garbage can, cleared fellow staff members out of the office, and called 911,” he wrote.

Panetta said his priority was the safety of his staff, adding that the staffer and her colleagues had been initially cleared by medical officials.

“These attempts to intimidate us will not deter us from doing our job,” he wrote.

“Despite these difficult circumstances, we remain committed to our democracy by continuing our service to the people of California’s 19th Congressional District.”

The envelope was sent from New York and appeared similar to other letters being investigated by federal authorities, according to Panetta’s office.

The office said the envelope had been torn open and quickly discarded, meaning the exact return address could not be confirmed.

The incident comes as the FBI, US Postal Inspection Service and US Capitol Police investigate a nationwide wave of suspicious letters mailed to congressional and election offices.

A notice distributed to Senate offices warned authorities were working to intercept further letters, but some could still reach their destinations.

The warning included a photo of one of the suspicious envelopes, postmarked “DSA” with a return address in New York City that the Democratic Socialists of America formerly listed on its membership forms.

The organization said it no longer occupies the address, which it stopped using in 2013.

Other California lawmakers, including Democratic Rep. Zoe Lofgren and Independent Rep. Kevin Kiley, also reported receiving suspicious mail, while Democratic US Sen. Alex Padilla said a suspicious package addressed to his office had been intercepted by the US Postal Service before it arrived.

Across the country, other members of Congress reporting suspicious mail included Reps. Seth Moulton, Maxwell Frost, Darren Soto, Ritchie Torres and Bonnie Watson Coleman, along with Sens. Mike Rounds, Chris Murphy, Lisa Blunt Rochester, Chris Coons, Kirsten Gillibrand and Amy Klobuchar.

Separately, the Santa Cruz County Sheriff’s Office responded to a report of potentially hazardous materials at the Santa Cruz County Government Building at 701 Ocean Street. The building was evacuated as a precaution, with no injuries reported.