CARBONDALE, Colo. (CBS4) – All Roaring Fork high schools were closed on Thursday and the elementary and middle schools placed on lock out after a threat made online that turned out to be a spam email.

The Carbondale Police Department notified Roaring Fork Schools early Thursday that an 18-year-old senior made threats of violence against his or her school in an online forum. The FBI was also involved in the investigation.

The threat was anonymous but the IP address was traced to the Carbondale area.

(credit: CBS)

(credit: CBS)

The Roaring Fork High School, Glenwood Springs High School and the Basalt High Schools were closed. The K-8 schools in Glenwood Springs and Carbondale were placed on lock out as a precaution.

A lock out means that all doors are locked, staff are on high alert and additional law enforcement are on site.

It turns out that similar threats were made across the U.S.

“At this point in time, from the information we have received from the FBI, the threat appears to be the result of a spam email. These emails have been received all over the United States. We learned today that neighboring school districts received almost identical threats: other school districts have recently received similar threats,” said Carbondale Police Chief Gene Schilling in a statement.

After determining there was no credible threat, all lock out restrictions were lifted on Thursday afternoon. High schools will remain closed for the remainder of the day but each school will determine which, if any, after school sports and activities will take place. All schools will resume classes on Friday.