Enlightenment School in Waterbury was evacuated due to an anonymous bomb threat Monday morning, according to the Waterbury Police Department.

The school, an alternative learning program for at-risk middle and high school-aged students located on Griggs Street in Waterbury, was safely evacuated after 10:30 a.m. Monday. Enlightenment students returned to class but were dismissed early, according to Waterbury Public Schools.

There have also been threats at Kennedy High School, Waterbury Arts Magnet School and Crosby High School in Waterbury over the past week.

Kennedy High School was safely evacuated for an anonymous bomb threat last Tuesday, according to police. Waterbury Arts Magnet School was put into a shelter-in-place order after receiving a threatening message on Thursday. A 17-year-old suspect was arrested and charged with first-degree threatening and second-degree breach of the peace in connection to the threat.

Last Friday, an increased police presence was requested at Crosby High School after police received a report of a social media threat against the school on Thursday afternoon.

At least 11 schools and school districts in Connecticut have received threats or have added additional security measures in response to threats in September. Eight threats have been made in the last week, including ones at E.O. Smith High School in Storrs, Windham High School, Manchester High School and Danbury High School.

There has been a rash of these types of threats throughout the country. The FBI has deemed the practice “swatting,” or making a false threat to draw a large police response to an area.

Waterbury Public Schools did not offer further comment. The threat is under investigation, police said.