Hinds County Sheriff Tyree Jones said in a tweet that six people were shot during the Mudbugs Festival at the state fairgrounds, including one suspected shooter who died at the scene. Police said they believe the incident involved multiple shooters.
The shooting took place shortly after 10 p.m. local time.
Jones said the scene has been secured and that at least two people have been taken in for questioning. All the individuals detained are juveniles.
Several shooting victims have been transported to local hospitals and are in stable condition.
The sheriff said at a press briefing that the investigation into the incident determined that a police officer shot and killed the deceased.
"We believe... that the victim that is deceased was actively involved in the incident that was reported regarding the gunfire," he said. "I will not reveal the name or the agency the officer is affiliated with. That is something that will come out... at a later date."
The incident is still under investigation and the Mississippi Bureau of Investigation has been called in to help with the case.