Firefighter investigators are on scene investigating the official cause of the fire that killed four firefighters, in southwest Houston. The 5-alarm fire that took the lives of the lives of those firefighters, happened at the Southwest Inn motel Friday afternoon, and caused the biggest loss in the Houston Fire Department's 175 year history.

Officials say the four firefighters who died at the Southwest Inn were looking for people they thought were still trapped in the burning building. Houston Fire Chief Terry Garrison says early invesigations give insight into what caused the fatalities.

"We do know there was a collapse and that is what caused our firefighters to get trapped," Garrison said.

The identities of the firefighters have been released. They are Captain Emergency Medical Technician (EMT) Matthew Renaud, 35, of Station 51;  Firefighter EMT Robert Garner, 29, of Station 68; Probationary Firefighter Anne Sullivan, 24, of Station 68; and Engineer Operator EMT Robert Bebee, 41, of Station 51.

Four Houston firefighters killed in massive motel fire near Southwest Freeway

Three of the firefighters pictured above are among the victims, including Sullivan, the most recent addition to the HFD, having graduated from the firefighter academy just last month.

An official statement was issued by Jeff Caynon, President of the Houston Professional Fire Fighters Association:

"Houston firefighters mourn the loss of our three brothers and our sister and will forever honor their sacrifices. Our association and the International Association of Fire Fighters are monitoring the conditions of the six injured firefighters and will be assisting them and their families in every way possible. This tragedy underscores the inherent dangers of our profession. Please keep Houston firefighters in your thoughts and prayers."

Mayor Annise Parker is asking for prayers for the families of the four fireghters who died, and the 14 injured, with all 14 still hospitalized, 12 stable, one had surgery, and another is critical in the burn unit.

"I ask for every Houstonian to offer their prayers for the families of these fallen firefighters but also to take a moment to think of what the job of the firefighter is and the dangers that they face every day." 

Houston's 100 Club is still accepting donations for the families of the families of the firefighters killed in the blaze.