(CNN) -- A Greyhound bus overturned in southeastern Pennsylvania early Saturday, injuring at least 20 people, a transportation spokesman said.
All of the injured have been relocated from the scene off the Pennsylvania Turnpike in Lancaster County and between 20 and 25 passengers people were transported to hospitals, said turnpike spokesman Carl DeSebo.
Helicopters were on standby, but no one was airlifted, he said.
Four passengers were uninjured and picked up by another Greyhound bus, company spokeswoman Maureen Richmond said. A total of 28 people had been on the bus, she said.The bus originated in New York with a destination of St. Louis, she said. The bus was on the Philadelphia to Columbus, Ohio leg of the trip at the time of the accident, she said.