Bensalem, Pennsylvania (CNN) -- About 100 vehicles were involved in a series of wrecks on the eastbound Pennsylvania Turnpike just north of Philadelphia on Friday morning, injuring at least 30 people and causing a traffic backup for hours over parts of two counties, officials said.
Glare from the rising sun and ice -- left over from a storm that dropped snow and freezing rain in the Philadelphia area -- might have been factors, state police Trooper Adam Reed said.
The wrecks started around 8:25 a.m. ET with a 14- or 15-vehicle collision in southern Bucks County, not far from New Jersey state line, said Bill Capone, spokesman for the Pennsylvania Turnpike Commission.
About 20 more sets of wrecks stretching for miles occurred on the turnpike, said Pat Ponticelli, Bensalem Township's deputy director of public safety.
Each apparently happeed as traffic slowed for crashes ahead.
In a number of areas, smashed vehicles were piled into each other with their front ends pointing in different directions, aerial video from CNN affiliate WPVI showed.
In one spot, at least nine vehicles appeared to be crunched in a jumbled group behind a tractor-trailer. In another, a couple of vehicles had come to rest against a jackknifed truck.
Thirty people were hurt, including five with serious, but non-life-threatening injuries, Reed said.
More than half of those injured were taken to Abington Memorial Hospital, where they were diagnosed with minor to moderate injuries, Dr. John J. Kelly, the chief of staff, said.
"I think we really saw mostly what we would call soft-tissue injuries, bumps and scrapes type of injuries," he said.
Traffic was moving again in one affected section of the turnpike by 2 p.m., video from CNN affiliate KYW showed.
Pennsylvania State Police said it hoped to have the road fully open by 5 p.m.
Heather Pasco, a driver involved in one of the crashes, told KYW that she thought she was a goner.
Pasco said she had stopped her car after she saw "cars bouncing off of the center divider." Although she stopped, a truck behind her didn't, she said.
"I looked in my rearview mirror, and there was a big ... truck right behind me, and he was trying to stop, but he was sliding and he slammed right into the back of me, which then made me slam into the car in front of me," she told KYW.
"I saw him (in the mirror), and I thought I was done," Pasco added. "The entire back end of my car is gone."
Police told her that her wreck was about 3.5 miles behind the initial crash, she said. She said the road, after snow and freezing rain had fallen in the area, wasn't "really plowed very well."
Traffic was backed up for miles, stretching west into adjacent Montgomery County.
CNN's John Newsome, Lena Jakobsson and John Fricke contributed to this report.