At least 13 people have died after a tour bus overturned on a highway in the Bronx, New York, early this morning, authorities said.

The accident happened at about 5:30 a.m. after a tractor trailer clipped the Worldwide Tour bus from behind on the New England Thruway at the Hutchinson River Parkway, according to the driver, who survived. The truck failed to stop after it hit the bus, police said.

The bus was heading southbound when it flipped on its side. It then skidded into the support post for a large highway sign. The post sliced through the length of the bus at the passenger seat level, officials said.

"Our - and the entire city's - prayers, thoughts and sympathies are with the victims, and their families and loved ones," said New York City Mayor Michael Bloomberg in a statement.

"Our prayers and sympathies are with the victims of this terrible tragedy and their family and friends."

The mayor said that the New York State Police is leading the investigation into the accident, and that city agencies have set up a Family Assistance Center to provide family members with information regarding their loved ones.

A total of 32 people were on board.

According to New York City Fire Department officials, six people were critically injured, two others suffered serious injuries and 11 suffered minor injuries. Rescuers supported the bus by wood planks.

"People were saying, 'Oh my God. Oh my God,' holding their hands on their heads," limo drive Homer Martinez told The Associated Press about the carnage at the scene of the accident. "I saw people telling other people not to go there, 'You don't want to see this.'"

Two nearby hospitals were used to treat the patients.

The bus was en route from Mohegan Sun casino in Connecticut to lower Manhattan where it was ultimately bound for Chinatown.

"Our heartfelt sympathy goes out to the families of all those involved in this morning's tragic bus accident in New York, " Mohegan Sun Chairman Bruce "Two Dogs" Bozsum and President Jeff Hartmann said in statement today.