Twenty to 25 injuries were reported, turnpike spokesman Carl DeFebo said, and rescue crews freed the woman who was trapped in the wreckage in a rural area about a mile east of the Lebanon-Lancaster exit.
The westbound bus had stopped in Philadelphia and was to stop again in Pittsburgh when it overturned about 6 a.m., DeFebo said.
Both westbound lanes of the turnpike were closed, forcing drivers off the interstate at the Reading exit to be rerouted to the Harrisburg East exit. Traffic was backed up for about three miles by the time vehicles were allowed to pass through on the shoulder of the highway around 8:30 a.m., while crews worked to upright the bus, DeFebo said.
At Lancaster General Hospital, one of three hospitals where DeFebo said victims were sent, staff were evaluating five patients, said nursing supervisor Jan Frailey.
No one could be reached at Greyhound's corporate office in Dallas early Saturday morning.
The crash is the latest in a series of tour bus accidents in the Northeast this year, though most of those involved smaller operators.
More than 30 people have been killed and more than 300 injured in tour bus accidents this year, according to Advocates for Highway and Auto Safety. That's more than in all of last year, when there were 30 killed and 272 injured in 28 crashes.
Tour bus industry safety has drawn heightened attention since the March crash of a bus returning to New York City's Chinatown after an overnight excursion to a Connecticut casino. Fifteen people were killed when the bus flipped onto its side and struck a pole, peeling off its roof.