Jessica Alba Presents Powerful Anti-Gun Violence Message at Teen Choice Awards (VIDEOS)

Jessica Alba stood shoulder to shoulder with young people who've lost family members to recent gun violence atrocities ... in the most poignant moment of Sunday's Teen Choice Awards.

Jessica and the teenagers made a plea to bring an end to the violence -- reminding the audience of the loved ones they'd lost in Newtown, Orlando, San Bernardino, Baton Rouge and more.

The tribute brought many people in the audience to tears.

Justin Timberlake had his own message about tolerance and Americans coming together.