A series of bomb threats were reported against Jewish community centers around the country Monday, according to authorities in several jurisdictions.

Many of those threats have been unsubstantiated and cleared, according to police--though some are ongoing. It is not clear whether or not the cases are connected.

In Miami Beach, Florida police said officials were investigating a “bomb threat received via telephone.” A little after noon local time, police said that no threat was located and that the street would reopen to traffic.

There was a bomb threat made to the Katie & Irwin Kahn Community Center in Columbia, South Carolina. Richland County, South Carolina deputies responded to the scene, and determined there was no validity to the threat.

A Nashville, Tennessee Jewish community center evacuated 100 people after a threat was called in, according to The Tennessean. The building was cleared a little after noon.

The Bender JCC in Rockville, Maryland was found to be all clear around 1:30 p.m. after a threat was phoned in, according to the organization. Around 300 people were evacuated, including a little over 200 from the preschool.

The Montgomery County Police Department said their investigation is ongoing.

Michael Feinstein, chief executive officer of the center, said that everyone's "a little exhausted" from the evacuation, but overall, everyone is OK.

"This is the first time we've had to evacuate for a bomb threat," Feinstein said. "[Today's events] seem to be a part of a nationwide trend that is really discouraging."

The New Castle County Police Department in Delaware tweeted that they were on the scene of a bomb threat at a Jewish community center and advised people to avoid the area “until further advised.” Officials tweeted that the scene was cleared a little after 2:30 p.m. local time.

According to Baltimore Jewish Life, a called-in bomb threat caused a Jewish community center in Baltimore to be evacuated. And, according to The Jewish Chronicle, Jewish schools across London, England, were evacuated due to bomb threats.

The sheriff’s office in Jacksonville, Florida, announced that a bomb threat called in to a Jewish Community Center that the building was “all clear” shortly after 1 p.m.

As of Monday afternoon, no agencies had drawn any connection between the incidents. Elise Jarvis, associate director for law enforcement outreach and communal security at the Anti-Defamation League, said that federal agencies are investigating all of the incidents.

"Each one is being investigated by law enforcement and is taken very seriously," Jarvis said.

She said that it's important for the community to know that, often, bomb threats are meant to be disruptive and aren't often substantial. And, she added, facilities should think about access control, and monitoring who and what enters a building.

"We appreciate every expression of solidarity with the community and reaching out, for sure," Jarvis said.