Robert Spencer said he often saw children playing on the porch of the home across the street from his in their northeast Baltimore neighborhood. When he looked out the window the next morning, the home was in flames.
Seven of the nine children who were in the home at the time of the fire are pictured.
Spencer ran toward the fire, but it was so big and hot he couldn't help them.
Six of the family's nine children were killed, while their mother and three of her other children were able to escape but were injured, a fire official said.
"I heard the kids crying. My daughter heard them. They said: 'Help, help,' and you know, couldn't save them, couldn't save them," Spencer said.
"There was just too much fire there."
All six bodies were recovered from the home on Thursday, fire department spokesman Chief Roman Clark said.
Clark said the children killed were two boys, ages nine months and two years; 3-year-old twin girls; and two girls, ages 10 and 11.
A GoFundMe page has been set up to help the family cope with the tragedy.
The page has recieved almost $100,000 in donations.
Investigators are searching for clues about what caused the fire.
Firefighters encountered heavy flames coming from all three floors of the home when they answered the call about 12:30 am local time on Thursday, and they attacked the blaze from outside, Clark said.
The third floor collapsed and the second floor partially collapsed and the fire was so hot that it melted parts of a car that had been parked in front of the house.
The children's mother and two boys, ages 4 and 5, were in critical condition on Thursday at a hospital.
Clark said an 8-year-old girl who helped rescue her younger brothers was in "good shape."