A New York tour bus driver faces charges after his bus crashed on a Delaware highway, killing two women and injuring several other people, authorities said late Tuesday.

Jinli Zhao, 56, of New York City is charged with two counts of operation of a vehicle causing death of another person in the Sunday crash, according to a statement from the Delaware State Police.

Hua'y Chen, 54, of New York City and Idil Bahsi, 30, of Istanbul, Turkey, died after the bus carrying 49 passengers flipped on a highway in New Castle, about 7 miles south of Wilmington.

Zhao was admitted to the Saint Francis Hospital in Wilmington with non-life threatening injuries and then released into police custody on Tuesday afternoon, when he was formally charged.

He was being held in lieu of $5,000 bond at Howard R. Young Correctional Institution in Wilmington.

Police said they do not believe alcohol or drugs were a factor in the crash and that further charges could be filed as the investigation continues.

Dozens of people were sent to hospitals after the bus flipped onto its roof and slid when Zhao lost control while trying to negotiate an exit ramp at what police said was an unsafe speed, according to the statement.

The bus slid on its roof down a grassy embankment and then turned onto its side before coming to a stop, police said.

Chen was partially ejected, pinned under the bus, and died at the scene, police said. Bahsi died hours later at a trauma center.

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