National Guard rescue teams were dispatched after heavy thunderstorms fed floods in Kentucky and Indiana, shutting down the University of Louisville, closing highways and cutting power to thousands of people.
About a dozen buildings at the university were without power and a dozen more on the main campus had some flooding, university spokesman Mark Hebert said.
Craig Buthod, director of Louisville's public library system, said that 3 1/2 feet of water inundated the main library's lower level. Tens of thousands of books were destroyed, he said.
National Weather Service hydrologist Mike Callahan said western Louisville was swamped by more than 6 inches of rain in three hours.
City officials said there were no reports of significant injuries.
In nearby Clark County, Ind., across the Ohio River from Louisville, floodwaters gushed over guardrails on Interstate 65, bringing traffic to a standstill.