The National Threat Assessment Center (NTAC) is in Bridgewater, VA. (USSS)
USSS started a Safe School Initiative in 2002.
Information and threat assessment manual can be found here:
securityantiterrorismtraining.org/MI/CARVER%20THREAT%20ASSESSMENT/United%2520States%2520Secret%2520Service_%2520National%2520Threat%2520Assessment%2520Center%2520(NTAC).html