Some Secret Service press releases on mass shootings (interesting statistics) and on VIP protection:

Report: Mass Attacks in Public Spaces- 2017, dated March 2018

https:// www.secretservice.gov/data/press/releases/2018/18-MAR/USSS_NTAC-Mass_Attacks_in_Public_Spaces-2017.pdf

Secret Service Response to Reports Director Alles Sought to Terminate Protection of First Family Members

https:// www.secretservice.gov/data/press/releases/2018/18-MAR/GPA_11-18_Secret_Service_Response_to_Reports_Director_Alles_Sought_to_Terminate_Protection_of_First_Family_Members.pdf

Dr. Lina Alathari, Chief, National Threat Assessment Center, United States Secret Service

Oral Testimony Before the United States Senate Committee on Judiciary March 14, 2018

https:// www.secretservice.gov/data/press/releases/2018/18-MAR/GPA_National_Threat_Assessment_Center_Testimony_Before_Senate_Judiciary_Committee.pdf

Secret Service press releases:

https:// www.secretservice.gov/press/releases/