Fire officials said a wall collapsed, killing the 42-year-old firefighter and injuring another.
The fire broke out at a warehouse on Polk Street near Wayside Drive just before 11 p.m. Wednesday and escalated very quickly.
Shortly after firefighters arrived, they called for a second alarm, and then, there was a mayday call after a wall collapsed.
Officials said one of the firefighter's injuries weren't severe, but the other firefighter, identified as Marcelo Garcia, was pronounced dead at the hospital.
Garcia had been with HFD for 10 years and spent the last six years at Station 23 on Lawndale Street on the southeast side.
"You're asking what type of man he was. He was a man who woke up every morning to come to work so he could help others and save lives. A hero, a true hero," Fire Chief Thomas Muñoz said.
"Firefighter Garcia left this morning expecting a good day, a hard day, a dangerous day, but he did expect to go home," Houston Mayor John Whitmire said. "I met him recently. Good looking, 42-year-old, young man with his life in front of him."
City leaders are asking for prayers for Garcia's family and his colleagues, some of whom had to pull him out of the warehouse.
"Here and out at the station still, it's a very sad day for the Houston Fire Department. We mourn together, we pray together, but more importantly, we honor our brother and his life, we honor it together," said Patrick "Marty" Lancton with the Houston Firefighter's Union.
Firefighters were able to extinguish the flames. Daylight video from the scene shows the charred building.
The investigation into what exactly sparked the flames is ongoing.
Fire Chief Thomas Muñoz said the warehouse was vacant. A man who works nearby told ABC13 he occasionally sees people working out of the building.