Las Vegas entertainers and country music stars reacted on social media overnight and into the day Monday in the wake of the deadly Mandalay Bay shooting targeting the Route 91 Harvest Festival. (See selected tweets below.)

Two of the country acts who were performing along with Jason Aldean, who was onstage when the shots first rang out, offered compelling first-hand accounts. “Spent I don’t know how long on the floor of a trailer behind the stage … Listening to that gunfire,” tweeted Chris Young. Jake Owen, who had performed before Aldean, tweeted, “I witnessed the most unimaginable event tonight.”

Country star Keith Urban, who was not in Vegas, tweeted that he was “stilled and speechless.” And Taylor Swift, who began as a country singer, tweeted, “There are no words to express the helplessness and sorrow my broken heart feels for the victims in Vegas and their families.” Cable network CMT’s Twitter handle retweeted numerous other reactions from the country music world. Country Music Hall of Fame and Museum CEO Kyle Young and his staff said in a statement, “Our hearts are broken and go out to all involved in the tragedy Sunday night in Las Vegas. At its core, country music is about community and love, and we stand with the victims and their families.”

Entertainers based on or playing the Strip also offered reactions. “Praying for all the innocent victims and their families,” tweeted Celine Dion, who has had a long-term residency but was not performing last night. Penn Jillette, a longtime Vegas resident and one-half of the magic duo Penn & Teller, tweeted, “We are safe. We know nothing but we are safe.”

Others with long-term Vegas runs, including Jennifer Lopez, Britney Spears and Billy Idol, have not yet publicly acknowledged the shooting.