Two of Hank Williams Jr.'s daughters remained in the intensive care unit at a Memphis hospital Thursday (March 16) after their SUV flipped over several times the day before on U.S. 61 near Dundee, Miss. Holly Williams, 25, was listed in stable but critical condition with a broken wrist, bruises and abrasions. Her sister, Hilary Williams, 27, underwent eight hours of emergency surgery Wednesday night and was scheduled for additional surgery Thursday. She sustained injuries to her hip and colon after she lost control of the Toyota 4-Runner she was driving. No other vehicles were involved, and there is no initial indication that drugs, alcohol or the weather contributed to the accident, according to the Mississippi Highway Patrol. The sisters were en route to a family funeral in Louisiana at the time of the accident. Holly Williams, an accomplished singer-songwriter, released her debut album in 2004.