MINNEAPOLIS — A crisis center in Minneapolis was forced to shut down its teen crisis hotline this week after it received hundreds of computer-generated calls in a cyberattack.

Bridge for Youth switched to another number Tuesday when the calls flooded the hotline. It’s the first known cyberattack in Minnesota, but part of a growing number aimed at extorting money from agencies that rely heavily on their phone lines.

Some of the calls were dead air and others were made by a man who asked for credit card numbers and money transfers with a deadline of one to five minutes, said Joan Countryman, the organization’s emergency services manager.

The agency was able to return to its regular number Wednesday, but the incident has left employees shaken.

“The bottom line from all of this was that our youth weren’t able to get through, and we weren’t able to conduct our business,” Countryman said.

In the so-called “telephony denial of service” scam, attackers use the Internet to jam phone lines with constant calls from randomly generated numbers. The scam has happened across the country, often targeting places where phone service is crucial, like hospitals and emergency call centers.