Detroit Police Chief James Craig announced arrests in recent threats made against Detroit schools.
More than two dozen schools in metro Detroit were shut down Thursday because of threats.
Craig issued a promise to track down and arrest anyone threatening a school.
He says three juveniles and one adult have already been arrested for numerous threats, and more people will soon be in custody.
"Each of those arrested could potentially face charges of terrorism and making threats online," he said. "That can come with a 20-year penalty."
Since Feb. 14, Detroit police have investigated 40 school threats; 34 of those were shooting threats, 2 were bombing threats and 4 were both.
At John R. King Academy, class was already in session when a bomb squad came out for a suspicious package. Kids were able to go home for a day after it was found to be safe.
Craig also said parents have to be responsible, and anyone found covering up for their child could also be charged.
