WAVERLY, Va. — A powerful storm system swept across the East Coast on Wednesday, killing four people in Virginia and knocking out power to tens of thousands of homes and businesses in the region.

A day earlier, the system spawned about two dozen tornadoes along the Gulf Coast, damaging hundreds of homes in Louisiana, Mississippi and Florida. Three people were killed and dozens were injured.

Forecasters had warned that more than 88 million people were at risk of seeing some sort of severe weather Wednesday. In the Midwest, heavy snow and biting winds led to mass flight cancellations at Chicago airports and school closings in several states.

In Virginia, Gov. Terry McAuliffe declared a state of emergency Wednesday evening. The tiny farming town of Waverly in the state’s peanut-growing region took the brunt of the storm. The Virginia State Police said at least five structures were damaged in the town of approximately 2,000.

The names of the three people killed there were not released, but state police spokeswoman Corinne Geller said in a statement that they were a 2-year-old child and two men, ages 50 and 26. She said their bodies were found about 300 yards from their mobile home.