A 12-year-old boy died after riding a roller coaster Thursday at the Disney MGM theme park, the latest in a string of tragedies that have stung Walt Disney World in recent years.

Disney officials turn away visitors at the closed Rock 'n' Roller Coaster at Disney World's MGM studios in Lake Buena Vista, Fla., Thursday, June 29, 2006. Earlier in the day, 12-year-old Michael Russell, of Kentucky, died while on the attraction. [AP]

Michael Russell of Fort Campbell, Ky., had ridden the Rock 'n' Roller Coaster with his parents and 7-year-old brother. When the minute-long ride was finished, Byron Russell noticed his son was limp, pulled him off the ride and performed CPR until paramedics arrived, Orange County sheriff's spokeswoman Barbara Miller said.

The boy was pronounced dead after he was taken by ambulance to Celebration Hospital at about 11:30 a.m., Disney said in a statement. The cause of death was not immediately determined.

"According to the family, he was a very healthy child," Miller said.

State officials say he is the ninth person to die at Disney World since 2003. At least 15 people have died at Disney's theme parks in Florida and California since 1989. At least some of the victims had pre-existing health conditions.

The park closed the Rock 'n' Roller Coaster but said a preliminary investigation showed the ride was operating normally.

The sheriff's office was investigating at the scene. State park safety officials were also notified.

A Disney spokesman said the company was assisting the family.

"Our deepest concerns are with the family," Disney spokesman Jacob DiPietre said.

A Disney Web site description of the ride says: "Zoom from 0-60 mph with the force of a supersonic F-14, take in high-speed loops and turns synchronized to a specially recorded Aerosmith soundtrack."

Theme park consultants said the ride is relatively tame.

"As roller coasters go that is not considered an ultra, ultra high-thrill coaster," said David Speigel, president of Cincinnati-based International Theme Park Services Inc. "It does have some high launch speeds, but it's more along the traditional lines of what roller coasters are today."

Disney MGM is among the Walt Disney Co.'s four parks in Florida.

Most of Disney's recent troubles have been over another ride -- Epcot's "Mission: Space," a rocketship attraction that simulates a flight to Mars. Two people have died in the last 12 months after going on the ride, which spins in a centrifuge that subjects riders to twice the normal force of gravity. Now Disney offers people an option to ride a tamer version of the ride that does not spin.