The ride is one of the park's most popular attractions

The incident happened on Disneyland's famous Big Thunder Mountain Railroad at about 1120 local time (1820 GMT), the officials said.

Los Angeles television station KCAL 9 said two children were among the injured.

"We have one fatality and 10 injured," John Nicoletti from the mayor of Anaheim's office said.

"The ride has been stabilised. Anaheim fire and police and Disneyland officials are on the scene," Mr Nicoletti said.

The roller coaster was closed and the area sealed off.

Anaheim police sergeant Rick Martinez told reporters that "at this point we don't believe sabotage was involved, but we are going to look at everything".

Park President Cynthia Harris was quoted by Reuters news agency: "We are shocked and saddened by this incident. Our hearts and prayers go out to the family of those involved."

World's largest

The Big Thunder Mountain Railroad coaster takes park visitors on a twisting and turning ride through representations of mineshafts and caverns of the Old West, past falling rocks and tumbling waterfalls.

Disney is the world's largest theme park operator, and last year it attracted nearly 13 million visitors.

Disney's main parks are Disneyland and Florida's Disney World, and there are also parks in Paris and Tokyo, with one in Hong Kong under construction.

Friday's fatality reportedly brings to 10 the number of people killed in the amusement park since it opened in 1955.

Past accidents at Disneyland parks include the apparent drowning at Disney World in Florida in 2002 of a man who reportedly jumped out of a tower and fell into a lagoon.