Students across the nation will be coming together in solidarity to protest gun violence and pay their respects to the lives lost in the Columbine shooting in 1999.

Marking the second national protest since the school shooting in Parkland, FL, activists, celebrities, and political figures are coming together to support students as they step out for social justice. Check out this list of social media shout-outs from your favorite celebrities:

Yoko Ono took to Twitter to share her support, saying, "When you do something that you really believe in, it will effect the whole world. I’m with you!"

To all the young participants of today’s #NationalSchoolWalkout: When you do something that you really believe in, it will effect the whole world. I’m with you! Love, yoko @schoolwalkoutUS
Mar 14

— Yoko Ono (@yokoono) April 20, 2018

Alyssa Milano tweeted chilling statistics about gun violence in schools:

An average of 47 children and teens are shot every day in the US.

This Friday, 2100+ schools across the country are walking out to stand up against gun violence.

Join a walkout near you: https://t.co/m2eWZlTncC #NationalSchoolWalkout pic.twitter.com/XKXWk4n5HK

— Alyssa Milano (@Alyssa_Milano) April 17, 2018

Robert De Niro actually wrote an excuse letter template for students to be able to join in the protest, detailing all of the educational and civic reasons this day is worth participating in:

BREAKING NEWS: Actor Robert DeNiro penned an "excuse letter," like the one a parents would sign for a teacher, for anyone who may need that extra boost of encouragement to participate in the #NationalSchoolWalkout. pic.twitter.com/QBO1EBN3BT

— Dave Vescio (@DaveVescio) April 20, 2018