Maryland case is fourth Six Flags roller coaster mishap this summer

Firefighters reach riders stranded on a roller coaster at Six Flags America in Upper Marlboro, Md., Sunday, Aug. 10, 2014. (AP Photo/Prince George's County Fire Dept., Marc Bashoor)

UPPER MARLBORO, Md. (WJLA/AP) - Officials at Six Flags America in Upper Marlboro were still trying to figure out Monday what caused a roller coaster to become stuck near the top of a ride, stranding two dozen people for several hours.

Prince George's County fire officials said it took about five hours Sunday to rescue 17 adults and seven children from the Joker's Jinx roller coaster.

On Monday, the park said in a statement that it is not yet sure why the train did not complete the ride. The park said the ride would remain closed until its staff and the ride manufacturer determines it is safe for operation.

The incident marked at least the fourth roller coaster mishap this summer at Six Flags' 16 amusement parks nationwide, according to a review of Internet news archives by

Just the day before the Maryland incident, a technical malfunction occurred Saturday on the Goliath roller coast at Six Flags over Georgia, stranding passengers who had to be removed by park staff from the ride.

Earlier this month, power on the Nitro roller coaster ride at the Six Flags Great Adventure park in Jackson, New Jersey failed, leaving passengers to make their way back to the ground by foot.

And four people on the Ninja roller coaster ride at the Six Flags Magic Mountain park in Los Angeles were hurt in July after one of the cars was derailed by a falling branch.

Despite the recent mishaps, the International Association of Amusement Parks and Attractions said its latest figures show that the chances of being hurt at an amusement park in the U.S. are one in 24 million.