Nearly two days after the deadliest mass shooting in modern US history, what set off the 64-year-old high-rolling gambler Stephen Paddock to gun down 59 people remains a big question mark.
What has become clear is the actions of first responders that saved some of the more than 500 people who were injured in the rampage.
150 first responders answered the emergency calls, from about 20 fire stations throughout southern Nevada.
Several of them spoke to reporters about what they saw and did in the first moments after the gunfire was heard.
The President of the Professional Firefighters of Nevada, Angelo Aragon, said 12 firefighters had been shot, including two who were performing CPR on victims at the time.
Aragon said the firefighters, "for the most part they have sustained survivable injuries."
Ben Cole, an off-duty paramedic and firefighter for the City of Las Vegas, was attending the country music festival with a friend while his daughter was working the concert with Community Ambulance.
After frantic moments trying to locate his daughter, once he heard the gunfire, Cole and his daughter reunited and both decided to stay and rendered first aid to victims.
Jessie Gomez, from the Clark County Fire Department, was attending the concert with several members of his close family. After the gunfire rang out he did his best to usher them to safety.
But, "there was a lady on the ground, she was bleeding from the head," Gomez said.
"I don't know if she was shot or whatever so I stopped. I had them continue and me and some other people helped her out."
Gomez described the overwhelming help that arrived at the shooting scene, but also how hard it was to persuade family members to leave deceased loved ones behind.