GREEN COVE SPRINGS, Fla. – A 13-year-old student is accused of threatening to “shoot up" a north Florida junior high school, sheriff's officials said.Investigators learned of the threat on Tuesday afternoon and the student was removed from classes sat Lake Asbury Junior High School in Green Cove Springs, said Clay County Sheriff Michelle Cook.The student, who lives in Orange Park, was arrested later Tuesday on two counts of written threat to kill or injure, an arrest report said.“The suspect was reported to have a Colt rifle in his hands during a chat and threatened to commit a shooting at Lake Asbury,” Cook said.She said the student admitted to making the threat.Clay County school district Superintendent David Broskie said another student.