Flanked by civic and religious leaders, Dallas Police Chief David Brown speaks to a crowd attending the vigil for five slain police officers, victims of a sniper attack, at Dallas’ Thanksgiving Square on July 8, 2016. Photo by Robert W. Hart for The Texas Tribune.

Obama, Bush to Speak at Dallas Memorial

President Barack Obama and his predecessor, former President George W. Bush, on Tuesday will lead the nation in a memorial service mourning the deaths of five Dallas police officers at the hands of a sniper who used a Black Lives Matter protest to launch an ambush on law enforcement.