Classes were dismissed early because of a bomb threat Thursday afternoon at Oak Forest High School, but nothing suspicious was ultimately found, according to authorities.

Authorities were called at 11:58 p.m. with reports that several notes had been left throughout the school’s campus at 15201 S. Central Ave. “indicating that the school would be blown up and seven different bombs would go off at various times,” according to a statement from Oak Forest police.

Students at the school, 15201 S. Central Ave. in Oak Forest, were dismissed at 1:15 p.m. “as an act of caution due to an ongoing situation,” according to a message to parents posted on the school’s website. The message added that “all students are safe.”

No suspicious devices were found when law enforcement searched the school with bomb-sniffing dogs, police said. The building was cleared by 3:15 p.m., but a criminal investigation into the threat was ongoing.

The Bremen High School District 228 Facebook account posted a comment Thursday afternoon that read, “There will be a formal statement forthcoming. All students and staff are safe and have been evacuated.”

The district’s Facebook page had not been updated as of Thursday evening.

Anyone with information was asked to call (708) 687-0376.