Although they were never supposed to be inside, many homeless people would spend many nights inside the boarded up Key Largo Casino.
"This place was an awesome blessing for a lot of people," one homeless man who spent nights inside told FOX5.
"It was shelter over their heads, especially during the winter time," said one homeless woman who often stayed inside.
But now, investigators with the Clark County Fire Department and the ATF said the fire that engulfed the building last week was intentionally set in two different locations, the front and the back.
Firefighters were on the scene fast, but even though a fire station is just a block away, most of the building was fully involved.
"Not only [did firefighters] put water on the exterior of it, but we also had to get inside the court yard area too because it was on the second and third floors," said Erik Newman, deputy chief with the Clark County Fire Department.
The ATF is now offering $5,000 to information leading to an arrest and conviction.
"The ATF takes very seriously the senseless act that not only placed in jeopardy the lives of 117 Clark County ... firefighters, but also any individuals that may have been living inside the abandoned structure," said ATF Resident Agent in Charge Jeffery Nardiello.
Some homeless find it hard to believe the fire was set by a person who would take refuge inside the casino.
"The homeless are not going to burn down their own homes," a homeless woman told FOX5.
Others admit the transient community often had those who were violent.
"There was arguments and stuff ... this wasn't the place to be out of your element and not aware of things," a homeless man told FOX5.
Copyright 2013 KVVU (KVVU Broadcasting Corporation). All rights reserved.