Six adults remain unaccounted for since the tornado, said Oklahoma Department of Emergency Management Director Albert Ashwood. It's possible those people had just "walked off" their properties or could still be found in the rubble, Ashwood said.
Secretary of Homeland Security Janet Napolitano visited the area Wednesday, pledging the government's support and urging people to register with the Federal Emergency Management Agency to see what aid they qualify for.
"We know that people are really hurting," she said. "There's a lot of recovery yet to do. .<!p>.<!p>. We will be here to stay until this recovery is complete. You have our commitment on that."
The National Weather Service said the tornado was a top-of-the-scale EF5 twister with winds of at least 200 mph -- the first EF5 tornado of 2013.
Dan Ramsey, president of the Independent Insurance Agents of Oklahoma, said a damage estimate in the low billions is "not surprising."
"Certainly it's in the hundreds of millions," Ramsey said. "I suppose seeing projections from similar disasters, it could stretch to a billion" or more.
With no reports of anyone still missing, the Oklahoma medical examiner's office announced that it has identified 23 of the 24 people who died in the tornado, and that 10 of those killed are children.
All of the children have been identified, among them 4-month-old Case Futrell and 7-month-old Sydnee Vargyas. Both babies died from head injuries. The eight other children ranged in age from 4 years to 9 years. Of those, six were suffocated and two died from massive injuries.