Police tape marks off the area where a shooting took place in downtown Dallas, Friday, July 8, 2016. Snipers opened fire on police officers in the heart of Dallas during protests over two recent fatal police shootings of black men. (AP Photo/LM Otero)

Dallas police ambush: The victims

Five police officers were shot and killed in downtown Dallas Thursday night during what was a peaceful protest over fatal police shootings o…

The U.S. Capitol was placed on lockdown for a short time Friday morning for a police situation (Chance Seales).

US Capitol lockdown ended

The Senate seargant at arms issued a lockdown alert for the building and visitor center.