David Dorsey, 42, and his wife Donna Sue Dorsey, 43, own the converted dairy barn and lived there with their three children in the second floor of the two-story structure, the two said Monday.
"It's terrible," David Dorsey said on Monday as the gutted home still smoldered.
The Dorseys, their children and Billy Nguyen, who rented a ground-floor apartment inside the home, escaped without injury as the fire engulfed the house, they said Monday.
Investigators learned that Carol Banks, 55, also lived in the house in a second ground-floor apartment, and she was at the house sometime Sunday.
Other residents didn't see Banks after the fire, and investigators who searched through the rubble found no trace of her.
Maryland State Police investigators, who were assisting the Maryland State Fire Marshal's office, towed Banks' green Honda Civic from the driveway beside the home.
The last time anyone from the residence saw Banks was early Sunday afternoon, said Nguyen, 43.
The fire apparently began in the portion of the house where Banks lived, Deputy Chief State Fire Marshal Allen Gosnell said Monday.
Investigators did not know Monday what caused the fire, but dogs trained in sniffing for fire accelerants - such as gasoline - did not identify the existence of any such chemicals, Gosnell said.
"We don't have a cause (of the fire) right now," Gosnell said.
David Dorsey said his family watched the Super Bowl Sunday night in the family living room on the second floor. Some of the children fell asleep in the living room, and he and his wife retired after the game was over, and fell asleep, he said.
Nguyen said he awoke to loud noises.
"Pop! Pop! Pop! Pop! It sounded like fireworks," Nguyen said. He said he pulled on a pair of pants, opened a door and saw smoke. Then, he said, he began yelling to wake the rest of the residents.
Thinking Banks might be in her apartment, he tried to call for her, but didn't see her, Nguyen said. He ran upstairs to the Dorsey's portion of the home and banged on a locked door until the Dorseys answered. Nguyen, the Dorseys and their three children - ages 9, 11 and 12 - got out through a side exit.
David Dorsey said the family would stay with friends nearby, and the Washington County Chapter of The American Red Cross made arrangements for Nguyen.