Four firefighters searching for people they thought might be trapped in a blazing Houston motel and restaurant Friday were killed when the part of the structure collapsed and ensnared them, authorities said. At least five other firefighters were hospitalized in the blaze that became the deadliest in the 118-year history of the Houston Fire Department. Flames were shooting from the roof of the Southwest Inn, along one of Houston's most heavily traveled freeways, U.S. Highway 59, and black smoke was blanketing the area as firefighters tried to extinguish the fire. Three firefighters were killed at the scene, while the fourth died at a hospital, according to the mayor's office and a medical examiner. Five other people were injured and were hospitalized for treatment of chest pains or leg injuries.