The law enforcement agency is seeking information on suspects in connection with the fires and posted photos of several on social media over the weekend. The agency confirmed that it will offer $2,500 for any info related to the case.
The fires were set at Walmarts in Gulfport and Biloxi, Mississippi, and two other Walmart locations around Mobile, Alabama.
On Twitter, the FBI posted six photos of masked people that the agency believes are suspects. FBI spokesperson Thomas Loftis told the media that they appeared to be “at least three people, two men and a woman.”
The first of these series of fire incidents started with a blaze on 27 May at a Walmart on Beltline Road in Mobile. Another blaze was reported at Walmart at Tillman’s Corner in Mobile in Alabama the next day.
Last week, a fire broke out at yet another Walmart location, this time in Gulfport in Mississippi. Then on Friday, another fire incident took place at a Walmart in neighbouring Biloxi, the agency said.
The Tillman’s Corner Walmart remains closed for business while the three others are now open, Mr Loftis said.
Scott Pope, a Walmart spokesperson, told reporters that their focus was on the safety of their “associates and customers.” He said: “We will continue to work closely with law enforcement officials to resolve this as quickly as possible.”