A mass shooting at a flea market in Houston killed two people during a Sunday marred by gun violence across the U.S. The Houston incident came hours after a gunman opened fire in a California church and a day after a teenager targeted Black shoppers in a Buffalo, New York, grocery store. Houston police did not immediately arrest the flea-market shooter, but suspect one of the injured people could be involved in what police believe began as an argument. Police say no innocent bystanders were shot at the busy Sunday market.