Shooter

Archive of Google Search Dec 5, 2016 - 04:25:41 UTC
https://archive.is/KHiJT

D.C. Police detain suspect with a weapon at Comet Ping Pong restaurant 
https://web.archive.org/web/20161204212228/https://www.washingtonpost.com/news/local/wp/2016/12/04/d-c-police-respond-to-report-of-a-man-with-a-gun-at-comet-ping-pong-restaurant/

UTC to EST (Washington D.C.) -5h, which means that the archived Google Search was taken at Dec 4,2016 - 23:25:41
The search shows articles which report the incident up to 20 hours before police was informed when you trust the reporting from the Washington Post that this happened at 3pm.