A New Orleans-bound Amtrak passenger train carrying approximately 400 passengers came to an abrupt halt in a 3,900-foot-long tunnel south of Union Station, and officials believe a child stopped the train by engaging an emergency brake.

Once in the tunnel Thursday night, diesel fumes from one of the engines sent at least 120 people to hospitals for observation, said Amtrak spokesman Cliff Black. None of the passengers was believed to be seriously ill, a Fire Department official said."Your throat got real dry, and we've got several children . . . their eyes are real red," said one adult on the train.

"We stopped, and parents told everybody to get low and cover their faces," said a young boy.

The Crescent, which originated in New York City, left Union Station about 6:40 p.m., but within minutes, crew members discovered the brakes were in an "emergency application," Black said.

The two engines pulling 16 passenger cars were turned off but not before some of those aboard the first two cars felt the effects of the fumes, Black said.