A tour bus barreling south for Manhattan overturned at high speed on a highway in the Bronx early Saturday and was sliced open by a sign stanchion in a shriek of rending metal that hurled riders about like rag dolls. Fourteen people were killed and 19 were injured, 5 of them critically, the authorities said.

Victims of the accident, which happened about 5:30 a.m. on Interstate 95 just across the Bronx line from Westchester County, were returning to Chinatown on a chartered bus from the Mohegan Sun casino in Uncasville, Conn. Some described grisly scenes of mayhem: at least one person decapitated, others maimed, people hanging upside down, victims gashed by flying glass, screaming in the darkness and struggling to get out. Some were thrown out on the ground, others were trapped in a maze of metal.

The crash cast a grim light on a nocturnal New York City subculture of overnight gamblers, many of them older Asian and Hispanic people, who take cheap buses from Chinatown to casinos in Connecticut and New Jersey, play the slots and tables for a few hours and catch an after-midnight bus home, usually sleeping on the trip back and often arriving just in time to get to return to work.

The driver, Ophadell Williams, 40, survived. He told the authorities that his bus was clipped by a passing tractor-trailer, which sped away, an assertion that the police later said was under investigation.