SANFORD, Fla. – A threat to a Seminole County middle school is under investigation Tuesday, prompting extra law enforcement at the Sanford campus, officials said.Seminole County Public Schools said a student made a threat to Millennium Middle School and authorities are investigating the credibility of the claim.Details about the threat have not been released.“Please know we take any and all threats seriously and investigate them to the fullest,” a school official said in a message to parents. “There will be an extra law enforcement presence added to the school (Tuesday) to ensure student and staff safety until this matter is resolved.”[TRENDING: Does coronavirus spread easily among children? | Gunman shoots 2 teens at skating rink | Michael.