Twin toddlers and their grandparents died Tuesday after a house caught fire overnight in Chillum, Maryland.
The twins' mother jumped from a second-floor window and is expected to survive her injuries.
Anna and Israel Omijie, both 2 years old, were killed, Prince George's County officials said. Their grandparents, Carolyn Omogbo, 55 and Sampson Omogbo, 63, also died after they were trapped inside a separate room.
Investigators found no evidence the rental home had working smoke detectors.
Prince George's County firefighters were called just after 2 a.m. to the 6700 block of Knollbrook Drive, where a total of seven people were when the blaze erupted.
"The wind was blowing and the fire was just out of control," neighbor Edmund Romero said.
Frantic family members who were able to escape told firefighters the toddlers and their grandparents were inside. The twins were pulled from the home almost immediately and taken to a children's hospital, where they died, Prince George's County Fire Chief Marc Bashoor said.
"I saw the little kids being carried out in an ambulance," Romero said. "I knew something bad had happened because the ambulance just left quietly."
The toddlers' grandparents were pronounced dead at the scene. The other two family members home at the time of the fire escaped safely.
"We did the very best we could to get inside to get those people out," fire department spokesman Mark Brady said.
The tragedy shocked the Nigerian family's close circle of friends.
"When I heard the [family's name] I just jumped into my car to come and confirm if it was the same address that I knew," family friend Festus Soho said.
"I don't know what to think of this. I cannot believe it," family friend Adele Benjamin said through tears.
The twins' mother was too distraught to speak on camera Tuesday evening. Her uncle, Vincent Omogbo said he was stunned.
"It's like a dream. I don't believe," he said. "My brother was very nice to everybody. He goes to church and he is very godly."
Firefighters went door-to-door and found several of the family's neighbors had no smoke detectors, or smoke detectors that didn't work.
The fire appears to have been accidental and is under investigation, officials said.
The tragedy occurred a year to the day since a massive fire killed six people in Annapolis, Maryland. An electrical fire that spread to a dry Christmas tree started the Jan. 19, 2015 fire that killed Don and Sandra Pyle and four of their grandchildren.