CNN Found a Bomb at Its New York Office. Confusion and ‘False Alarms’ Followed.

They turned out to contain scrap metal and children’s books in California and a USB drive in New York Gov. Andrew M. Cuomo’s office in Manhattan.

But people across the country were not taking any chances with suspicious packages after six pipe bombs were sent to prominent Democrats on the East Coast.

Confusion, caution and even some panic spread in New York and other cities after the explosive devices were found in packages addressed to former President Barack Obama, former Secretary of State Hillary Clinton and others who have faced sharp criticism from the right.

Media outlets seemed to be especially vigilant after a device was found in New York City, at the CNN offices in Time Warner Center. Its envelope was addressed to Obama’s CIA director, John O. Brennan.

That discovery prompted the mass evacuation of the Time Warner complex shortly after 10 a.m. Eastern time. CNN employees said that an alarm went off and they were told to leave the building, but that they were not told why.

M.J. Lee, a political reporter at the network, said on Twitter that she was directed to go to a staircase “immediately” at the time of the evacuation.

“I wasn’t allowed to grab a coat or any of my belongings,” she wrote.

By that point, news of the packages sent to Obama and Clinton had been widely reported. But once the situation at CNN became clear, it seemed to set off a flurry of reports of suspicious packages across the country.

News organizations in particular seemed to take precautions on Wednesday. The device at CNN was found two days after a shooting at a Fox affiliate in Washington, which deepened the concerns over newsroom security that were raised when a gunman killed five people at a newspaper in Annapolis, Maryland, in June.

In San Diego, a building that houses The San Diego Union-Tribune newspaper, an office for Sen. Kamala Harris, D-Calif., and other businesses was evacuated Wednesday morning after five boxes were spotted in a patio area.

The police closed the surrounding blocks and conducted an investigation, but the boxes only contained seemingly ordinary items: a football, a shoe, two children’s books and an empty bag of potato chips.

The boxes were not addressed, according to Kevin Wadhams, a lieutenant with the San Diego Police Department, and were left by an unknown person overnight.

Wadhams said that while officers were aware of the wave of pipe bombs being found, the police investigation was routine. But not everyone who worked in the building was so certain.

“It’s in context of all the other packages,” said Nathan Otto, 35, who works for the city auditor in San Diego, as he headed back to work after the evacuation. “Who knows how many false alarms are going around the country now?”

There were certainly others. The police were called to the Los Angeles Times building in El Segundo, California, after reports that suspicious envelopes were delivered there. The building was not evacuated, and officials said the packages did not contain explosive devices.

And as the police in San Diego blocked off streets, hundreds of miles north, in Fresno, California, a bomb squad was sent to the offices of KSEE-TV and KGPE-TV after a suspicious package was found in the television stations’ shared parking lot.

Inside the package, police officers found trash and scrap metal, Mark Hudson, a lieutenant in the department, said. An officer at the scene said it appeared the detritus “might have been left there by some homeless person,” Hudson said.

In New York at the Time Warner Center, Agne Nasevioiute, 31, said she was attending a marketing and technology conference when security officers interrupted and told attendees to leave.

“It’s my first time in New York and this happens,” Nasevioiute, who works for a company in Lithuania, said. “But I’m happy that nothing serious happened, and that’s the most important thing.”

About an hour after the evacuation, some phones in the city buzzed and blared with an emergency warning that urged people near the building, at West 58th Street and Eighth Avenue, to shelter in place while the police investigated.

Two nearby public schools, Independence High School and the High School for Environmental Studies, were also put under the same shelter in place order, the city’s Department of Education said. It lasted less than an hour.

With information scant, some residents said the alert frightened rather than informed.

Others pointed to the message’s imperfect location targeting. Some people in the area of the Time Warner Center said they did not receive it, while people who said they were elsewhere in New York did.

A follow-up alert sent an hour later that said a bomb squad had removed the device did little to quell fears.

New York’s governor was also on a heightened state of alert. On Wednesday afternoon, Cuomo said in a news conference that a device was sent to his office in Midtown Manhattan. The building was evacuated, with workers spilling onto the streets as the police investigated.

The device turned out to be an unrelated thumb drive, a New York police spokesman said.

Richard Azzopardi, a spokesman for the governor, said on Twitter that the device contained “computer files” on the far-right group the Proud Boys.