RELATED: Market Street reopens in San Francisco following bomb threat
They forced evacuations of centers in San Rafael and Palo Alto, plus the San Francisco office of the Anti-Defamation League due to a threatening phone call.
"They said that they had a bomb," said Central Pacific Regional Director for the Anti-Defamation League Seth Brysk. "That they had planted a bomb and they had planned to kill us."
Police shut down Market Street between Grand Avenue and Kearny Streets.
"That's really scary to hear that there was a bomb threat," said Semhar Gebreyesus of San Francisco.
Within a half hour, the Oshman Family Jewish Community Center in Palo Alto got a call too. Classes were canceled and children were evacuated.
"And to have them to have to be evacuated because of a threat that they may be blown up is terrorizing and fear-inducing," Brysk added.
More than 20 Jewish facilities across the country received threats Monday, including the Osher Marin Jewish Community Center in San Rafael.
"Oh my gosh, one of 20," said Gebreyesus. "That's very sad news to hear that."
"We'd like to see a plan of action put into place and this demands leadership and it demands leadership from the top," Brysk told ABC7 News.
Officials evacuated hundreds of people before a bomb-sniffing dog gave the all-clear.
"We just appreciate everyone cooperating," Ewins told ABC7 News. "We had people evacuate and we also had people shelter-in-place."
The ADL reports that more than 90 threats or incidents of anti-Semitism within the last two months.