Jewish community centers in several states were evacuated on Monday after they reported bomb threats, according to the organizations' social media accounts and local media reports. (Reuters)

More than a dozen bomb threats were reported Monday at Jewish centers in the United States and Britain, and new reports were still coming in as the FBI continued to investigate.

More than 500 students and employees were evacuated from the Alper Jewish community campus in the Miami-Dade area in the late morning, according to ABC affiliate WPLG.

At almost the same time, a bomb threat was called in to a Miami Beach center, the outlet reported.

No device was found in either location — nor was a bomb found at a center in Tenafly, N.J., where a preschool was evacuated as a news chopper circled overhead.

Nor in Nashville, or Columbia, S.C., or Rockville, Md., or at the Siegel Jewish Community Center north of Wilmington, Del. — where an operator asked the caller for details about the supposed bomb but only got a dial tone.

“It’s disturbing,” said Elise Jarvis, who directs the Anti-Defamation League’s security programs, and has so far counted a dozen threats in the United States on Monday, with more coming in.

Even more threats were reported at centers in the United Kingdom, which dealt with a rash of bomb hoaxes against Jewish centers nearly a year ago.

No one was hurt in those cases. But a few weeks later, a Florida man was arrested and accused of plotting to blow up a synagogue after getting a fake bomb from an undercover FBI agent.

Jarvis said many of today’s calls appear to come from the same phone number.

“Should an institution be hit by something like this, it should be taken extremely seriously,” she said. “At the same time, these are tactics to disrupt operations, and scare tactics.”

She said a few Jewish organizations reported bomb threats last week, too, though nowhere near Monday’s scale.

The Anti-Defamation League was in touch with the Department of Homeland Security, Jarvis said. The spokesperson for the FBI said the agency was aware of the threats but provided no details.