(CNN) At least eight Walmart locations have received threats over the past week after deadly shootings at two stores in recent weeks, law enforcement agencies said.

In Florida, Richard D. Clayton, 26, was arrested after he allegedly posted a threat on Facebook that he was about to have his gun returned and people should stay away from Walmart.

He was detained Friday after an investigation by various agencies, including the FBI, the Winter Park Police Department and the Florida Department of Law Enforcement.

He allegedly made a threat Tuesday on a Facebook post stating, "3 more days of probation left then I get my AR-15 back. Don't go to Walmart next week," the Florida Department of Law Enforcement said.