The service began with the victims' families processing in one by one as firefighters throughout the stadium stood and saluted them. As many as 40,000 people were expected to remember the four who died Friday - the deadliest day in the Houston Fire Department's 118-year history.
Dozens of fire trucks and emergency services vehicles from New Orleans, Dallas and elsewhere formed a long procession on flag-lined streets leading to the stadium.
"This is what the firefighter family is all about," said Teresa Gonzales, whose husband is a 30-year Houston firefighter. "It's awesome they're doing this for the families (of the victims)."
Pictures of the four victims were on video screens in the cavernous stadium, normally home to the NFL's Houston Texans. Behind the stage, two fire trucks, ladders extended, held up a giant American flag. Similar trucks outside hoisted U.S. and Texas flags.
The names of the four were in lights on scrolling boards that ring the inside of the stadium.
Killed in the fire when the motel structure collapsed were Capt. Matthew Renaud, 35, who had been with the department for 11½ years; engineer operator Robert Bebee, 41, who joined the department almost 12 years ago; firefighter Robert Garner, 29, who joined the department 2½ years ago; and Anne Sullivan, 24, a probationary firefighter who had graduated in April from the Houston Fire Department Academy.
Representatives from each of their families, along with Houston Mayor Annise Parker, Fire Chief Terry Garrison and other fire officials, were speaking from a stage adorned with flowers. Garrison was to present to the grieving families flags that flew over the U.S. Capitol last Friday.
Opening and closing prayers were being led by Cardinal Daniel DiNardo of the Roman Catholic Archdiocese of Galveston-Houston.
Investigators at the scene of the five-alarm blaze at the Southwest Inn have said they are focusing on an attic and the kitchen area of a restaurant connected to the motel.
Deputy Chief Ed Arthur, who heads the department's arson division, said Tuesday he expected the physical examination of the rubble to take about 10 days but a report of the findings could take months.
"The investigation is dedicated to our heroes, our fallen firefighter friends," he said.