Jason Aldean, Brad Paisley and More Celebs React to Mass Shooting in Las Vegas

Country music star Jason Aldean, who was onstage as bullets started raining down on the Route 91 festival on Sunday night, was one of many celebrities who expressed shock, horror and sympathy as authorities were still counting the dead on Monday.

"Tonight has been beyond horrific," the singer wrote on Instagram. "I still don't know what to say but wanted to let everyone know that me and my crew are safe. 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."

Singer Ariana Grande, who was performing in Manchester when a bombing killed 22 concertgoers last May, called for increased gun control in a powerful tweet.

"My heart is breaking for Las Vegas," she wrote. "We need love, unity, peace, gun control & for people to look at this & call this what it is = terrorism."

Country singer Chris Young, who also attended the festival on Sunday, tweeted that he took cover "on the floor of a trailer behind the stage." He added in a follow-up tweet, "I'm not gonna say anything else other than I'm lucky to be alive. As are many others... and so many people are gone... this is heartbreaking."

Country singer Jake Owen, who performed before Aldean, shared that he was safe, but "others aren't" and ask for prayers.

Laura Robson, a 23-year-old British tennis player, was attending the concert at the time of the shooting and responded to a fan on Twitter that she was safe but shaken. "I'm okay," Robson wrote. "We were right there.. sounded like fireworks at first then everyone started running. Scary shit."

Singer-songwriter Clay Aiken, who was not at the festival, criticized those who say "don't politicize a tragedy" in the wake of the shooting.

Selma director Ava DuVernay tweeted, "The lone wolf. The local shooter. The gunman. Any and everything, but terrorist. Wonder why."

Emmy Rossum, known for her role as Fiona Gallagher in Shameless, called on Donald Trump for stricter gun control laws.

Famed country singer Brad Paisley was not at the festival but tweeted out a message of support to all who were, as did singer Céline Dion.

Taylor Swift tweeted she felt "helplessness and sorrow" for the shooting victims and their families.

Singer-song writer Ryan Adams, who was not at the festival, tweeted out a strong anti-gun message.

Comedian Michael Ian Black called the National Rifle Association "a terrorist organization."

Barack Obama shared his condolences to those affected by what he called a "senseless tragedy."

Hillary Clinton urged all to "put politics aside" and "stand up to the NRA."

Australian singer-songwriter Sia, who was not at the concert, tweeted out a warning on Twitter to her followers in Las Vegas, writing, "Please, if you are in Las Vegas, take cover there are multiple shooters on the loose, twenty people are dead. Find cover and hide."

Author Stephen King wrote on Twitter, "Condolences to all of those scarred by the violence in Las Vegas last night. We are with you."

Hamilton creator Lin-Manuel Miranda tweeted, "Heartbroken by the news out of Las Vegas. Praying for those of us waiting for news from loved ones who went to hear live music on a Sunday."

Actor George Takei shared his gratitude for the Las Vegas first responders on the scene.

Early Monday morning Chance the Rapper tweeted out simply, "Lord help us."

The comments come after a concert turned into a nightmare when gunman Stephen Paddock, 64, open fire on the crowd from the Mandalay Bay Hotel and Casino across the street from the festival, cops said.