Thirty patients were transferred from the Moore campus to Norman's other hospital sites to the south, and all of the Moore patients and staff were all accounted for, the system said.

But the tornado blocked Interstate 35, which runs north-south through the city, forcing some residents on the north side of town to flock to Oklahoma City hospitals such as Integris and 750-bed OU Medical Center.

Internists at OU Medical Center worked long into the night to discharge patients and give the hospital the capacity to care for the incoming flood of victims. Staff treated 94 patients, including 51 children, between its main campus and Children's Hospital of Oklahoma, hospital officials said at a news conference. No fatalities had been reported at the hospital.

As of Tuesday afternoon, the death toll stood at 24, including nine children, though the number has been rising and falling since the tornado struck.

Patients who did find their way to the hospitals seemed to have less-severe head and blunt-force injuries than would have been expected based on past storms, doctors at Integris Southwest and OU Medical Center said. However, the sheer volume of patients was the medical staff's biggest challenge.

But the hospitals in the area have handled that volume well, largely as a result of the state's trauma planning after a severe tornado hit the state in 1999, said Dr. Bob Letton, OU Medicine's pediatric medical director. Patients needing treatment have been transferred to hospitals and treated faster than 1999, he said. Without that planning, the death toll would have been “much higher.”

Both hospitals experienced loss of water pressure Tuesday, which Hogan said was in some ways more crippling than a power failure because of hygiene concerns.