Explosive devices targeting U.S. Senator Kamala Harris and billionaire Democratic activist Tom Steyer were intercepted Friday in what authorities called a Florida man’s plot to mail more than a dozen pipe bombs to politicians and public figures critical of President Trump.

An improvised explosive device, or IED, sent in a package addressed to Harris was discovered by a post office worker in Sacramento, according to the FBI. A second bomb in a package addressed to Steyer was found at a mail processing facility at 1625 Rollins Rd. in Burlingame.

The packages were discovered on the same day a nationwide manhunt ended with the arrest of Cesar Sayoc, 56, who was taken into custody in Plantation, Fla. His fingerprints and DNA were allegedly found on another bomb mailed to Rep. Maxine Waters, D-Los Angeles.

At least 13 packages containing pipe bombs were sent to Democratic Party leaders including former President Barack Obama, former Vice President Joe Biden and Trump’s 2016 election opponent, Hillary Clinton, authorities said.

Postal service workers in Burlingame were escorted out of the Rollins Road facility after the device was discovered. Agents continued investigating the scene Friday afternoon.

The device was taken off-site, according to Burlingame police. FBI officials in San Francisco tweeted that the package was “rendered safe” around 1 p.m.

Mail carrier Cynthia Maffei said she was about to leave the facility around 10 a.m. when the package sent to Steyer was found by another employee. Thirty minutes later, Maffei said, the post office was evacuated.

“They were seriously telling us to get out now,” she said. “It makes me nervous.”

Supervisors told her to “forget everything,” get out of the building and not come back for the day, Maffei said.

Steyer ran the hedge fund Farallon Capital for 26 years and has donated $65 million to Democratic candidates and environmental causes during the 2016 elections, according to Forbes. He has also led an effort to have Trump impeached.

At a youth summit Friday, Trump said he was “pleased” with the arrest of Sayoc, but many Democratic leaders blamed the president’s rhetoric for creating a dangerous political climate.

Lily Adams, a spokeswoman in Harris’ office, said it was time for “leaders across the political spectrum to take seriously the power they hold,” adding that elected officials should “elevate our discourse and bring people together.”

Steyer tweeted out a statement calling on the Republican Party to denounce any attacks “on the rights and dignity of any American.”

“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 wrote. “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.”

In total, 13 IEDs consisting of six inches of PVC pipe, a small clock, battery, wiring and energetic material have been found, according to the criminal complaint against Sayoc. FBI Director Christopher Wray warned that more packages could be found in the coming days.

Authorities declined to comment on the motive behind the bombs, though Sayoc, who has a long arrest record, had expressed contempt for liberals and reverence for Trump, including on social media. In Florida, authorities seized Sayoc’s white van, which was adorned with pictures of Trump and stickers critical of Democratic leaders and news network CNN, another of the alleged bomber’s targets.

Rep. Jackie Speier, D-Hillsborough, told The Chronicle that Sayoc’s targets are people on “the president’s enemies list.”

Trump “has gone out of his way to throw verbal bombs,” Speier said. “He elevates people who do violent things. This could have been catastrophic to our country.”

Attorney General Jeff Sessions said he “didn’t know” why Democrats were targeted.

Sayoc was charged with five federal crimes that included transporting explosives across state lines, illegally mailing explosives, threatening former presidents and other people, threatening interstate communications, and assaulting assaulting federal officers, according to the criminal complaint.

He could face up to 48 years in prison if convicted, Sessions said.

Prior to the announcement of the arrest, Trump was criticized for bashing CNN in a Friday morning tweet that used quotation marks around the word “bomb.”

Republicans are doing so well in early voting, and at the polls, and now this “Bomb” stuff happens and the momentum greatly slows - news not talking politics. Very unfortunate, what is going on. Republicans, go out and vote! — Donald J. Trump (@realDonaldTrump) October 26, 2018

“Republicans are doing so well in early voting, and at the polls, and now this ‘Bomb’ stuff happens and the momentum greatly slows — news not talking politics,” Trump wrote. “Very unfortunate, what is going on. Republicans, go out and vote!”

Chronicle staff writer Jill Tucker contributed to this story.

Sarah Ravani and Gwendolyn Wu are San Francisco Chronicle staff writers. Email: sravani@sfchronicle.com, gwendolyn.wu@sfchronicle.com Twitter: @SarRavani @gwendolynawu