A tornado touched down briefly in the St. Louis suburb of University City, damaging some homes and bringing down trees and power lines.
No injuries were immediately reported.
Jim Sieveking, of the National Weather Service in St. Louis, says the tornado touched down at 5:23 a.m. Thursday as a strong storm system with intense lightning and heavy rain moved through the St. Louis region.
Video from St. Louis media showed trees blocking streets, damage to some homes and power lines on the ground. Some people were asked to leave their homes in a neighborhood where crews are working to find the source of a strong gas smell. About 7,000 people were without power shortly after the storm.