Chloe Grace Moretz and Gabrielle Union were among the celebrities stunned by a fatal shooting on the University of California, Los Angeles (UCLA) campus on Wednesday (01Jun16).
Two men were shot and killed and the university site was placed on lock down as police swarmed the school.
Hours after the news was first reported, Los Angeles Police Chief Charlie Beck announced the shooting was a murder-suicide, and lifted the lock down.
Celebrities took to social media as they watched the story unfold on local news stations, with actress Moretz writing: "UCLA school shooting, When is enough enough. It's time to change our gun laws and change America", and former student Union added, "Prayers up for UCLA!"
Singer Charlie Puth wrote: "UCLA you are in my prayers right now. Such a senseless act", and actress Ariel Winter offered: "My thoughts & prayers are with @UCLA & all the students & families affected by today."
There were also tweeted thoughts and tributes from Ellen DeGeneres and filmmaker Kevin Smith.
Students and faculty on campus also turned to social media to share photos and information during the lock down. Some posted photos of the police and emergency personnel on campus, while others offered up shots of their safe rooms and the efforts they went to to barricade themselves inside.