GROTON, Conn. (WTNH) — Police received at least 18 different “swatting” calls Friday for Connecticut schools, according to various authorities.

A “swatting” call is when an individual calls police to report an active shooter situation, when there is not one.

No threats were found at any of the schools.

The calls started at about 9 a.m., when Stamford police received a report that there was an active shooter at Stamford High School. The high school, along with other schools in the district, were locked down as a precaution. The lockdowns were lifted at all schools by 9:30 a.m. after authorities deemed the call was a hoax.

At 9:10 a.m., Westport police went to Staples High School after hearing a report that there was an active shooter at the scene. Police searched the building, found nothing and then kept officers outside as a precaution.

About an hour later, Groton police went to Fitch High School, Groton Middle School and Grasso Southeastern Technical School after hearing a call about an active shooter in the area. The schools went into lockdown and officers searched each building. The call appeared to be a recording, according to officials.

At 10:45 a.m., Windham High School was placed into lockdown, and all Windham were under a shelter-in-place order, after police received a report of an active threat at Windham High School.

In Norwich, police responded at about 11:10 a.m. to Norwich Technical High School after hearing a report there was an active shooter at the scene. The school went into lockdown and police searched the building.

Kate Dias, the president of the Connecticut Education Association, called the threats “shocking, appalling, and downright dangerous.”

Dias said that similar calls were reported in districts in California, Florida, New Jersey and South Carolina.

“For Connecticut, these false incidents are extremely traumatic and painful and a vivid reminder of the shooting at Sandy Hook Elementary School that took 26 innocent lives nearly 10 years ago,” she said in a written statement.

Connecticut schools received at least nine threats last month. No danger was ever found, and the incidents led to the arrests of four people. This month, two schools have received threats, and one led to the arrest of an 11-year-old.