coanchor, byron pitts. >> we're driving into the heart of downtown. >> i can't look at it and not seethe terror. >> reporter: for linsey hartman, independence day will never be the same. >> i've come to this parade my entire life. my daughter scarlet was standing right here, dancing in the street, having the time of her life when the first shots started to fire up. >> reporter: the highland park fourth of july shooting. one of more than 600 mass shootings this year. linsey, her husband danny, and their 4-year-old daughter scarlet were there when horror happened. >> breaking news for you, a horrific scene unfolding. this is just outside of chicago. >> i looked at my husband, and he looked at me, and we just nonverbally knew that we had to run for our and i said, "protect her, don't worry about me, it will slow you down, just go." it's still pretty rough. you know. there's a lot of emotions that are still very much at the surface. >> like what? >> fear. gratitude. terror. >> what did you lose that day, do you think? >> the best way i can describe it is, i don't feel safe. my world has j

here now, byron pitts. >>> green pickup truck in front of me. >> how are you doing today, sir?rter: a routine traffic stop involving these two men. >> thank you. i need backup. >> reporter: but the driver isn't cooperating. the situation quickly escalates. >> i just need to go. >> reporter: becoming dangerous. >> my driver's license and i'll get out of here. >> put your hands behind your back, please. >> reporter: an ambush. had it been real, the outcome could have been fatal. >> who's the backup officer? >> i am. >> what was called in? >> guys, we talked about this. we have to be observant on our traffic stop. >> reporter: this is missouri's lincoln university, an hbcu, one of the 107 historically black colleges and universities in america. >> tomorrow will be physically demanding. >> reporter: and these young men and women, the inaugural class, in the very first police academy at an hbcu. >> a lot of jobs are stressful. but this job in particular puts your life on the line every single day. >> reporter: a groundbreaking program born out of necessity. today 66% of police offic

here is my "nightline" co-anchor byron pitts. >> tell everybody you know to vote for senator warnock, tell them not to vote if they're not going to. >> reporter: in the final push to the finish line of the midterm elections, democrats hoping to crush the competition with star power from dave matthews. ♪ crazy how you make it all all right, love ♪ >> reporter: former president barack obama. >> you deserve a senator you can be proud of. >> reporter: republicans also ut all contentious and critical contest for the u.s. senate in georgia. >> i got a simple message. help is on the way for georgia. >> herschel walker is winning this race. >> reporter: former football star herschel walker trying to unseat incumbent democratic senator reverend raphael warnock. >> i'm running for reelection not because i'm in love with politics but because i'm in love with change. >> i'm going to fight for the people. and that's who i need to fight for, not for washington, d.c. >> reporter: the two facing off for the second time in a month after neither man cleared the 50% threshold in the general, triggering