A young girl and her 61-year-old grandfather remained in critical condition Tuesday at an Atlanta hospital, more than a day after being severely burned in a fire at Spring Street Apartments, a fire official said.

Gainesville Fire Chief Jon Canada said that the girl, nearly 2 years old, and her grandfather remained in Grady Memorial Hospital’s burn unit, where they were airlifted after a 9 a.m. fire Monday at the low-income apartments off Jesse Jewell Parkway across from Northeast Georgia Medical Center.

As of late Tuesday afternoon, their condition was still "very critical," Canada said.

Fire officials are not releasing the names of the victims. The girl sustained second- and third-degree burns over 70 percent of her body, while her grandfather had seond-degree burns on his face, arms and hands, officials said.

The cause of the fire remains under investigation. Canada said it could be several days before officials release a cause.

"We’ve got some things that came to light today that we’re looking at," Canada said.

The girl’s 38-year-old mother and 3-year-old brother were treated for smoke inhalation at Northeast Georgia Medical Center and later released.

The fire was contained to a single unit of the apartment complex, and Gainesville police were able to rescue three victims by the time firefighters arrived shortly before 9 a.m.

Family members are helping the woman and her son with lodging, Canada said.