PHOENIX -- A tornado hit a shopping mall near Tupelo, Miss. on Monday.
Mayor Jason Shelton said several injuries were being reported.
Residents in the area were told to seek immediate shelter in a basement or interior room of a sturdy building as the tornado approached.
A tornado emergency was declared for several counties in Mississippi.
The tornado was part of a large, powerful storm moving across the United States. Over the weekend, 16 people were killed across three states.
A tornado that touched down near Vilonia, Ark. was about a half-mile wide and claimed 14 of the 16 killed. The tornado would likely be rated as the nation's strongest to date this year, as it has the potential to be at least an EF3 storm, which has winds greater than 136 mph, National Weather Service meteorologist Jeff Hood said.
Sunday was the third anniversary of the day 122 separate tornadoes struck parts of Mississippi, Alabama, Tennessee, Virginia and Georgia and killed 316 people.
The Associated Press contributed to this report.