In neighboring Maryland, where 76,000 customers were in the dark, power companies gave a restoration estimate of Friday. More than 7,000 New Jersey customers also lacked electricity.
Officials pleaded with people not to use generators or gas grills indoors after 20 to 25 people in the Philadelphia area were taken to hospitals with carbon monoxide poisoning.
Robert Kagel, deputy director for emergency management in Chester County, told WCAU-TV that some of the more seriously injured were transferred to Philadelphia hospitals for treatment.
While some homeowners fired up generators, others, like Dave Dixon and his wife, are relying on the generosity of others to power them through. They planned to stay with their friends overnight Thursday — and possibly longer.
"If we wear out our welcome, we'll get a hotel," said Dixon, whose home in the Philadelphia suburbs went dark at 6 a.m. Wednesday.
In Wyncote, a town just north of Philadelphia, Hannah Reimer took to Facebook to ask for a kerosene heater and recommendations on where to buy the fuel.
"And it worked! Someone from my church, who has power, has a kerosene heater and my husband is picking it up now," she said Wednesday night.
Reimer and her husband then planned to pay it forward, inviting their neighbors to spend the night.
"Our neighbors don't have heat, either," she said. "Or a kerosene heater."
Thousands of utility workers descended on the Philadelphia suburbs to get the lights back on.
It was the second-worst storm in PECO's history — eclipsed only by Superstorm Sandy in 2012 — with the utility reporting 623,000 outages at one point Wednesday. "We know that this is going to take multiple days," PECO spokeswoman Cathy Engel Menendez said.
About 3,500 employees and contractors were working to restore power, while an additional 1,000 linemen from utilities as far as Chicago were expected to join the company's efforts, she said.