my "nightline" coanchor byron pitts goes inside the group for our week-long series "america in black and white." ♪ ♪ glory glory hallelujah >> reporter: today the city of dallas taking time to mourn. gathering to remember the lives of five officers killed in last week's horrific attack. putting politics aside, president obama and the first lady, hand if hand with former president george w. bush and first lady laura bush. the president delivering a sermon of sorts. >> i'm here to insist we are not as divided as we seem. and i know that because i know america. i know how far we've come against impossible odds. >> reporter: his poignant observation that in the audience, mourning of all sides. >> i see people who mourn for the five officers we lost, also weep for the families of alton sterling and fill lawn dough castille. i see what's possible when we recognize we are one american family. >> reporter: thousands having paid their respects over the last few days. these squad cars outside dallas police headquarters. a mill shift memorial filled with messages of hope and loved. the 11 injur

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