A teenager was killed at the Six Flags over Georgia theme park in Austell, Georgia, US, after he scaled a fence to get into a restricted area that is off-limits to visitors.

The 17-year-old, named in local media as Asia Leeshawn Ferguson, climbed over two security fences before being struck by the Batman roller coaster. He died instantly from head injuries suffered during the incident on Saturday 28 June. None of the riders were injured by the impact.

According to police and Six Flags officials it is still unclear why the teen ventured into the restricted area with another friend, but it is thought that he was either trying to take a short cut back into the park after lunch, or attempting to retrieve a baseball cap he had dropped earlier in the day, while riding the Batman coaster.

According to park spokesperson Hela Sheth, Ferguson and a friend climbed over two 6-foot fences - a wrought-iron style park perimeter fence and a second chainlink fence around the Batman ride. Signs about 40 to 50 feet apart on the outer fence warn that it is a "restricted area" for "authorized personnel only."

"Our security and safety personnel responded immediately, and Cobb County Fire Department was on site just minutes after the incident occurred," Sheth added.

"The medical examiner arrived on scene and confirmed that the 17-year-old male was killed instantaneously. Our thoughts and prayers are with the family."