FBI officials intercepted a second suspicious package addressed to California billionaire Tom Steyer on Thursday night, authorities said, a week after he and other high-profile Democrats, among others, were sent improvised explosive devices by mail.

Like the earlier packages, Thursday’s parcel, which was found at a mail processing facility in Burlingame, was discovered by FBI officials before it arrived at the recipient’s address. Officials did not describe its contents.

“The package was very similar in appearance to the others,” Katherine Zackel, a spokeswoman for the FBI’s San Francisco office.

The package was “rendered safe” by FBI bomb technicians at an off-site location, Zackel said. Detectives with the FBI, U.S. Postal Inspector and Bureau of Alcohol, Tobacco, Firearms and Explosives are investigating the mailing.

Last week, a package containing an improved explosive device addressed to Steyer was found in the same facility, prompting an evacuation.

That day, a Florida man was arrested for sending more than a dozen improvised explosive devices to politicians and prominent public figures, many of whom had been critical of President Trump, including Sen. Kamala Harris.

Officials have not yet said whether suspect Cesar Sayoc is believed to be responsible for the packages mailed to Steyer.

Earlier this week, postal workers intercepted a package addressed to CNN at a postal facility in Atlanta. In total, 16 packages have been recovered by FBI investigators.

Steyer, who ran the hedge fund Farallon Capital for 26 years and is now a prominent Democratic activist, led an effort to impeach President Trump this year.

“We are seeing a systematic attack on our democracy and our rule of law that extends much further than just one isolated terrorist in Florida,” Steyer tweeted after the first package was found last Friday. “Whether it’s voter suppression, voter intimidation, attacks on our free press, gerrymandering, or attempted violence — the trust and norms that are the actual basis of our civil society and political system are being eroded.”

On Friday, Sayoc was transported to New York to face federal charges for the pipe-bomb mailings. He was charged with five counts of transporting explosives across state lines, illegally mailing explosives, threatening former presidents and other people, threatening interstate communications and assaulting federal officers, according to the criminal complaint.

Gwendolyn Wu is a San Francisco Chronicle staff writer. Email: gwendolyn.wu@sfchronicle.com Twitter: @gwendolynawu