Get the latest from TODAY

Sign up for our newsletter
/ Source: TODAY
By Gina Vivinetto

It's a painful day to remember, but it's one we'll never forget.

Dec. 14 marks five years since the day a young man named Adam Lanza fatally shot 20 schoolchildren and six adults at Sandy Hook Elementary School in Newtown, Connecticut. Lanza turned his gun on himself before police could apprehend him.

On Thursday, Reese Witherspoon, Olivia Wilde and other celebrities took to social media to share their emotional memories of the unthinkable tragedy. Many of them encouraged fans to fight for stricter gun legislation.

"I’m in tears remembering these little innocent lives that were lost #SandyHook. 5 years ago today. Praying for their families," Witherspoon wrote.

Here are just a few of the other heartfelt messages posted by celebrities.

TODAY's Willie Geist offered a stirring reflection on what happened in Newtown on Dec. 14, 2012, and the anguish that the shootings caused so many families.

"Thinking about the 20 sets of parents who were dropping their first graders at Sandy Hook Elementary right about now, 5 years ago, the 6 families of staff members who gave their lives for someone else's children, and what they all have lived with every day since. RIP," he wrote.

Former TODAY anchor Katie Couric also shared a tribute to the victims.