More than 12,000 students in New Jersey were given an unscheduled day off Thursday after a bomb threat forced the closings of nearly 50 schools.

Officials said the threat was sent to the mayor of Emerson in a note that appeared to be computer-generated. The note claimed "All three schools will be blown out on Thursday, Sept. 20th at 11:30 a.m." The note also mentioned two schools in nearby towns.

Bomb-sniffing dogs walked school grounds at the Bergen County schools instead of students. Police found no explosives at the schools, but insist they will continue the investigation and prosecute offenders.

"It's a crime, and I'll do whatever I can to make sure that person is punished," said Bergen County Sheriff Leo McGuire.

For additional coverage of the bomb threat on Bergen schools, go to channel 612 on your iO digital cable box and click on iO Extra.Related informationEmerson School District