When Steve Speyer found out about the horror unfolding in Las Vegas, he sent a text to his friend Charleston Hartfield, a police officer in Las Vegas.
"You good brother?," it read.
He never got a reply.
Later he found out Hartfield was among the 59 people killed when gunman Stephen Paddock opened fire from the 32nd floor of the Mandalay Bay Resort - targeting those attending the Route 91 Harvest Festival country music show.
Hartfield, a married father of a son and daughter, was a US military veteran and youth football coach. He also recently published a book, describing his life working on the streets of Las Vegas as a police officer.
The 34-year-old posted an image of the Route 91 country music festival on his Facebook page Sunday evening, hours before the gunman struck.
The shooting is now considered the deadliest in US history and police have warned the death toll may rise.
Friend Troy Rhett told the Las Vegas Review-Journal, "He was probably busy helping others ... I don't know a better man than Charles.
Tributes have been paid on social media to the late officer.
"This man was not just a good man," Speyer said on Facebook. "He was a great man, as kind as they come and cared about everyone."
Allen Rhett wrote: "To my very good friend Charleston Hartfield and his family. You will be missed so much as you are the symbol of what it means to be a great person, friend, husband, father and coach."
Amanda Robinson added: "Such an amazing man, our hearts are truly broken, Charleston Hartfield, you my friend have touched so many lives and mentored so many young lives!"
The attack has been claimed by Isis but the FBI has said there are no links to international terrorism.
Police said they had no information about Paddock's motive, he had no criminal record and was not believed to be connected to any militant group.
The 64-year-old gunman, from Nevada, killed himself before police stormed his room on the 32nd floor of the hotel.
Paddock is believed to have used a high-powered assault rifle to blast his victims at the end of a performance by country music star Aldean.