We spoke to Nelson, a 16-year veteran of METRO, about what he saw as he rode alone on his route on 19th Street near Shepherd just after 9am.
"I was coming down 19th Street and a lady came running out hollering and crying, said she needed help and I just went back there to see if there was anybody in the house," Nelson said. "I came across a man who was half out of the house, stumbling, bloody, and his shirt had been burned off of him. ... I guess my adrenaline was going so fast, I just had to get him out. ... And I just helped him sit down by the tree."
Nelson said he went back around the house to see if someone else was inside, but said he couldn't go any further because the flames grew overwhelming.
Janna Pineda, a neighbor, said, "It was bad. I saw a lot of flames. And it's right next to my house. And I got really scared."
"There wasn't enough time to call 911," Nelson said. "Anybody's doing that much crying, somebody is in there. And that was all I needed to know."
Asked what compelled him to help, Nelson said, "The love of life -- for myself and others. That's it."
Nelson said what happened -- and what he did -- hasn't hit him yet. He said he just hope the man hurt in the fire is OK.
The man in the home was taken to Memorial Hermann Hospital Medical Center for severe burns while Nelson suffered minor burns on his neck, hands and arms and was sent to Memorial Northwest Hospital.
Nelson's wife, Mia, picked him up at the hospital and was relieved to find him with only minor injuries.
Plz keep our Operator and those involved in Heights fire in your prayers. We'll keep you updated on situation. http://t.co/LSqFZtT4hH— METRO Houston (@METROHouston) July 31, 2015
There's no word yet on the cause of the fire.
METRO says they're trying to figure out a way to recognize Nelson's act of kindness.