A road trip by a college women's lacrosse team turned to horror when their bus crashed into a tree, killing their pregnant coach, her unborn child, and the driver.

Seton Hill University team players and coaches were among the 23 people aboard when the bus veered off the Pennsylvania Turnpike and crashed just before 9am yesterday local time. No other vehicle was involved.

Coach Kristina Quigley, 30, of Greensburg, Pennsylvania, was flown to hospital but later died from her injuries, Cumberland County authorities said. Ms Quigley was about six months' pregnant and her unborn child did not survive.

The bus driver, Anthony Guaetta, 61, of Johnstown, Pennsylvania, died at the scene.

The other passengers were removed from the bus within an hour and taken to hospitals as a precaution. The collision appeared to have shorn away the front left side of the bus, which rested upright about 70 yards from the road at the bottom of a grassy slope.

The lacrosse team was on its way to play at Millersville University, about 50 miles from the crash site in central Pennsylvania, for its fourth game of the year.

Seton Hill, a Catholic school of about 2,500 students near Pittsburgh, said a memorial Mass on campus would be held tonight.

Ms Quigley, a native of Baltimore, was married and had a young son, the school said. She was in her second season as coach and came to the school after spending three years as coach at Erskine College in South Carolina. She also worked as an assistant coach at Duquesne, her alma mater in Pittsburgh.

The bus operator, Mlaker Charter & Tours, of Davidsville, Pennsylvania, was up to date on its inspections, which included bus and driver safety checks, said Jennifer Kocher, a spokeswoman for the state Public Utility Commission, which regulates bus companies.

On Tuesday, another bus carrying college lacrosse players from a Vermont team was hit by a sports car that spun out of control on a wet highway in upstate New York, sending the bus toppling on to its side. One person in the car died.