First lady Michelle Obama, left, hugs Dallas Police Chief David Brown, as President Barack Obama, right, watches during a memorial service at the Morton H. Meyerson Symphony Center with the families of the fallen police officers, Tuesday, in Dallas. Five police officers were killed and several injured during a shooting in downtown Dallas last Thursday night. (AP Photo/Eric Gay)

They stood in a line, clasping hands as a choir sang, Democrat and Republican, black and white, politician and cop. Led by President Barack Obama and his predecessor George W. Bush, they honored the five Dallas policemen slain last week and urged Americans to rise above racial divides and reject despair.

The scene unfolded at a memorial service after a week when Americans were jarred by video images of angry crowds protesting police killings of black men in Louisiana and Minnesota and heard the screams of Thursday's sniper attack on police in Dallas by a black former U.S. soldier who had said he wanted to "kill white people"/Reuters. More here.