Another witness, CiCi Nelson, told CNN she was in line to ride Goliath when the rollercoaster returned and she saw an empty seat with a loose safety bar and a girl covered in blood.

Nelson described a scene of hysteria, adding that one man was “freaking out, saying someone fell off”.

Brittany Landry, who believes she saw the man ejected from the rollercoaster, told Fox News she was in tears.

“I broke because we were just on there,” Landry said.

A park spokesperson said in a statement that its team and local authorities had responded immediately and that they were co-operating on an investigation into the incident.

Mableton Mayor Michael Owens said the city’s public safety director was co-ordinating with local police and park security on the situation.

The Goliath ride opened in 2006, and it has an elevation of 200ft (60m), a 170ft plunge, a 540-degree spiral, and a speed of up to 70mph (112km/h), according to the park website. On its “thrill scale”, Six Flags ranks Goliath at level four out of five.

Six Flags is the largest amusement park operator in North America, with 20 amusement parks, 14 water parks and nine resorts across Canada, the US and Mexico.

The death in Georgia comes just weeks after one of Six Flags’ parks in southern California announced it would close the popular X2 roller coaster after more than 100 people alleged brain injuries from the ride.

Six Flags said that ride had passed a range of safety tests, but that it had decided to retire the attraction because it was “the right thing to do”.