Shawn Mendes just honored victims of gun violence with an emotional tribute at the Billboard Music Awards ... and with the help of students from Marjory Stoneman Douglas.
Shawn took the stage Sunday to perform his song "Youth," and was joined by singer Khalid ... who's featured on the song. Toward the end of the performance, multiple students from MSD's choir came out as well to help him finish out the tune.
We broke the story ... Shawn was aiming to send an uplifting message with the Parkland students' cameo -- especially in the wake of another school shooting this week that left 10 people dead.
As you can see ... the message was well received by those there. A standing ovation ... and not a dry eye in the room.