Bloomberg's Jeff Mason recounts his experience of being at the Washington venue where an active shooter briefly breached the security perimeter, and discusses some of the security implications of the incident. -------- More on Bloomberg Television and Markets Like this video? Subscribe and turn on notifications so you don't miss any videos from Bloomberg Markets & Finance: https://tinyurl.com/ysu5b8a9 Visit http://www.bloomberg.com for business news & analysis, up-to-the-minute market data,