SIOUX FALLS, S.D. (KELO.com) What Sioux Falls School Superintendent Brian Maher calls an act of "cyber-terrorism" led to extra security at Roosevelt High School on Thursday.
"The act was unfounded, at least at this point, and untraceable," said Maher at a hastily called news conference.
Maher says the email threatened gun violence against the school. Authorities quickly investigated and concluded the threat came from outside the area and was a hoax.
School continued as usual, but with extra security officers on hand.
Maher thanked the police and school staff.
"While this was an incredible nuisance and caused a great deal of anxiety, in the end, I'm proud of how folks inside the district handled it."
Maher termed it cyber-terrorism because of similar threats received in the past year.