Lily Clark, 5, was with her parents and three brothers and sisters on April 28 at the Sonic location in Clarksville, Tenn., when she fell into a below-ground container for used restaurant grease, located under landscaping a few feet away from patio tables, and was "engulfed in grease," her mother, Dana Clark, said.
The container is typically closed with a removable cover marked "Warning: Do not enter. Poison gas.", the Clarksville Leaf-Chronicle said Tuesday.
The cover was "dislodged" when the child fell in, a statement from Sonic spokeswoman Christi Woodworth said.
Lily's father, Michael Clark, pulled her out. She was taken to Gateway Medical Center in Clarksville, and except for grease in her ears, received a clean bill of health, the newspaper reported.
Sonic apologized for the incident, noting it is the responsibility of vendors to remove and replace coverings.
Dana Clark said she and her husband are now talking with lawyers, adding, "This needs to be a lesson to all restaurants. You can't have stuff like that open near children."