Screencap: KCNC-TV

Dozens of schools in the United States and Britain were evacuated on Monday after receiving a wave of apparently coordinated threatening phone calls, USA Today reports. None of the threats were found to be legitimate.

According to NBC News, the calls targeted elementary, middle and high schools in Colorado, Delaware, Florida, Illinois, Iowa, Maine, Massachusetts, Minnesota, Montana, New Hampshire, North Dakota, Maryland, New York, Oregon, Rhode Island, South Dakota, Utah, Vermont, Washington, Wisconsin, Wyoming. The Daily Mail reports 26 schools in the United Kingdom were closed as well. From NBC News:

Many American schools said they recorded calls from an electronically disguised voice reporting a bomb, multiple police agencies told NBC News. Many said the calls came in around 2 to 2:30 p.m. ET.

In Britain, several schools received a 90-second recorded call from a voice with an American accent promising that “shrapnel” would “take children’s the heads off,” according to multiple news reports. Many of those schools reported that the calls also came in about the same time, in this case about 10 a.m. local time.

In a statement, the FBI said they’re aware of the bomb threats and will provide assistance to local authorities as needed.

“As always, we encourage the public to remain vigilant and to promptly report suspicious activities which could represent a threat to public safety,” said the FBI.