At least 50 people are dead and more than 400 injured after the massacre at Route 91 Harvest Festival, the deadliest mass shooting in U.S. history

Dozens of celebrities, from Lorde and Gina Rodriguez to Brad Paisley and Barack Obama, are tweeting in response to the mass shooting at Route 91 Harvest Festival in Las Vegas, which left at least 50 dead and more than 400 injured, making the attack the deadliest mass shooting in U.S. history.

The shooting happened during a performance by Jason Aldean, who ran off the stage as the gunman opened fire from the 32nd floor of the Mandalay Bay hotel and casino.

“Tonight has been beyond horrific. I still don’t know what to say but wanted to let everyone know that me and my crew are safe,” Aldean wrote on Instagram. “My Thoughts and prayers go out to everyone involved tonight. It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night.” He added the hashtags #heartbroken and #stopthehate.

Several country singers have posted condolences and support on social media, including Kelsea Ballerini, Chris Young, and Brad Paisely.

Other celebrities, including former president Barack Obama, also reacted with condolensces, anger, heartbreak, and concern.

President Donald Trump also posted his condolences on Twitter.