By David Ingram and Mark Hosenball
NEW YORK/WASHINGTON (Reuters) - A wave of telephone bomb threats to 16 Jewish community centers in nine U.S. states may have originated from the same number and been placed by at least one individual and an automated calling system, security officials said on Tuesday.
The Federal Bureau of Investigation is looking into the calls, which led to evacuations at some of the community centers on Monday, but resulted in no attacks or injuries. Police who searched the centers found no bombs.
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The FBI has not named any suspects or described a likely motive for the bomb threats, and it was not clear why the centers in the U.S. Northeast, Mid-Atlantic and South regions were targeted.
Some of the phone calls were made using an automated "robocall" system, while others were placed live by at least one individual, said Paul Goldenberg, national director of the Secure Community Network, a nonprofit group that advises Jewish groups on security.
Automated calling has been used for threats before, including in January 2016 when a string of apparent hoaxes disrupted U.S. schools, but the tactic is still considered unusual.
"Bomb threats to Jewish communities are nothing new," Goldenberg said in a phone interview. "What's extraordinary is that we had so many in such a short period of time."
The phone calls were made to Jewish community centers in Delaware, Florida, Georgia, Maryland, New Jersey, North Carolina, Pennsylvania, South Carolina and Tennessee.
All of the centers were back to normal operations on Tuesday after being declared bomb-free, the JCC Association of North America said. The centers offer children's programs, fitness rooms and other services.
It was not clear if the calls were related to bomb threats against several British schools. Most of those schools were Jewish, and an analysis indicated the calls there came from separate countries, a source who monitors security threats said, speaking on condition of anonymity.
It was possible that the U.S. incidents "may have originated from the same phone number," said Oren Segal, director of the Anti-Defamation League's Center on Extremism, which he said was working with the community centers and law enforcement.
FBI officials declined to comment on the progress of their investigation but said in a statement that they were encouraging the public to be vigilant and to promptly report suspicious activities that could be a threat to public safety.
Jewish organizations would step up security training and staff to counter threats, Goldenberg said.
(Reporting by David Ingram in New York and Mark Hosenball in Washington, editing by G Crosse)