(Reuters) - A tour bus with about 50 passengers overturned on a Delaware highway on Sunday, leaving two women dead and sending the others to area hospitals with injuries ranging from mild to severe, state police said.

Rescue teams backed by medical helicopters pulled people through the windows of the bus, which flipped over at around 4:20 p.m. local time (2020 GMT) on a highway in New Castle, about 7 miles (11 km) south of Wilmington, Delaware State Police Sergeant Paul Shavack said.

A 54-year-old woman was killed after she was thrown from the bus. A 30-year-old woman was pronounced dead at a local hospital late on Sunday night from trauma suffered during the crash, Shavack said.

Two children were hurt, but their condition was unknown. Three to five other people were in critical condition, said Shavack, who described the vehicle as a single-deck tour bus.

At least 48 other people on the bus were taken to local hospitals with non-life threatening injuries that included broken bones, cuts and bruises, he said.

Officials had earlier said the crash occurred in the adjacent city of Bear.

The bus was taking a modest curve on an off ramp when it drove off the roadway, flipped onto its roof, and slid down a grass embankment, Shavack said.

The passengers were part of a sightseeing group returning to New York City from Washington D.C. near the end of a three-day tour, he said.

The bus company was identified by officials as AM USA Express, with offices in New York City's Chinatown, a hub for motor coach transport across the northeastern United States.

There was no reply to telephone calls to a number listed as AM USA Express' office.

State officials are investigating the crash.

(Reporting by Victoria Cavaliere in Seattle; Additional reporting by Curtis Skinner; Editing by Fiona Ortiz, Sandra Maler and Clarence Fernandez)