Their nerves have been rattled but leaders of Jewish community centres and organizations in the United States are vowing to stay strong, and safe, in the face of repeated death threats made by anonymous callers since the start of the year.
More than 120 bomb threats have been phoned in to dozens of Jewish community centres and schools in 36 states, according to the Anti-Defamation League, whose offices in San Francisco and New York City were also on the receiving end of bomb threats. None have proven to be true.
But that doesn't make them any less worrisome to deal with, said Leslie Sax, executive director of the Gordon Jewish Community Center in Nashville, Tenn. The centre received a threatening phone call on Jan. 9, then two more in the following weeks.
"We're steeling ourselves for the next time," she said in an interview.
Sax said her centre's members are trying not to let the threats cause fear and disruption, but that's easier said than done.
"They are threatening to kill Jews. There is no denying it is personal," she said, adding that people feel both angry and sad that this is happening.
It's not just bomb threats. Jewish groups say there has been an uptick in harassment, vandalism and other anti-Semitic activity in recent months. Three cemeteries were also desecrated in the last few weeks.
The community centres are being targeted simultaneously. On Monday, for example, 31 calls were made to 23 centres and eight schools everywhere from California on the west coast to Rhode Island and Delaware in the east. Some sound like automated robocalls that use voice disguising technology.
The FBI arrested a 31-year-old man in connection with some of the calls, but according to a New York Times report he's not believed to be connected to the majority of the calls.
"We have no idea who the actual caller is," said Michael Feinstein, chief executive officer at Bender Jewish Community Center of Greater Washington. His centre in Maryland was targeted the same day as the one in Nashville in January.
"It was a cold, windy day," he recalled as he described how 200 pre-school children were evacuated along with members using the fitness centre and the pool. Swimmers were given foil blankets for warmth as they fled the building.
"I think we were a little shaken," Feinstein said about the experience, which so far has been an isolated one. But the frequency of threats to other centres means they are constantly preparing to get the next call, he said. "It's exhausting."
His and other centres are well-equipped with emergency response plans and some have increased security measures in light of the recent threats.
The Secure Community Network, a group focused on security for the Jewish community, on Thursday announced the formation of a new advisory council in response to the threats.
Paul Goldenberg, national director of the Secure Community Network, offered praise for the FBI and the Department of Homeland Security in a call with reporters. He said he's confident that whoever is responsible for the threats will be discovered and prosecuted.
"We are not going to change the way we live," he vowed.
Jonathan Greenblatt, national director and CEO of the Anti-Defamation League, called the anti-Semitic incidents alarming, scary and unnerving, but made the same promise as Goldenberg.
"We will not be deterred," he said. "We will not be daunted."
Goldenberg also noted that for every threatening call the ADL receives, it gets 10 more from people expressing support.
He said he's satisfied with the FBI and DHS, but would like to see President Donald Trump's White House take action.
The president has been criticized for not condemning the incidents sooner and for telling a Jewish reporter to sit down and be quiet when he asked the president at a news conference what action he planned to take.
Trump has since called the threats horrible and painful and made note of them during his speech to Congress on Tuesday night.
Goldenberg said that was a positive step but that Trump needs to "move from words to action quickly."
Trump should direct the department of justice to launch a civil rights investigation, he said, and convene an inter-agency task force to address anti-Semitism.
"Ultimately, he will be judged not by his rhetoric but by his results," he said.
Some Jewish groups were already upset with the White House when it did not mention Jews in a statement commemorating Holocaust Remembrance Day. And last year, Trump's campaign blasted back after accusations of promoting anti-Semitic language and imagery.
Mark Potok of the Southern Poverty Law Center, a group that advocates against bigotry, said he thinks Trump has little credibility when he condemns anti-Semitism.
Trump has reacted sharply to critics, saying at a news conference in February that he is the "least anti-Semitic person that you've ever seen in your entire life."
Trump has also noted that his daughter Ivanka converted to Judaism to marry her husband Jared Kushner, who works for Trump.
Potok didn't accuse Trump of being anti-Semitic — but he said he thinks the president has avoided disavowing those who are. In his view, the president pilloried a variety of minority groups during his campaign and that gave some people a sense of permission to act out.
"These were people who had these feelings under the surface and now feel emboldened to act on them," Potok said.
Feinstein, from the centre in Maryland that was threatened, also said he thinks that "uncivil discourse" during the election season spurred bigots to commit hate crimes.
As frightening as the bomb threat experience was, Feinstein said one positive outcome has been the expression of support for the Jewish community in its wake. His centre received emails and letters from people around the country, he said.
"That's been really uplifting."