This story is no longer being updated, click here for the latest Saturday updates, including Philadelphia Mayor Jim Kenney's reaction to what he called a "frightening" blast.
A massive fire and series of explosions rocked a South Philadelphia refinery complex, the largest on the East Coast, early Friday morning. The blast jolted people awake miles from the scene, but no major injuries were reported.
The blaze at the Philadelphia Energy Solutions refinery erupted shortly after 4 a.m. City emergency management sounded early warning sirens at 5:30 a.m. and issued a shelter-in-place for the area immediately around the complex. It was later lifted.
The fire still burned from a hole in a gas line as of Saturday morning, PES said in a statement.
It would continue to burn until the refinery is able to turn off a valve, according to Philadelphia fire and emergency management officials.
It remains too dangerous to access the valve, city Deputy Fire Commissioner Craig Murphy said at a news conference, adding that the fire is contained but not yet declared under control.
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Officials with the energy company did not attend the news conference, but did release a new statement Saturday morning.
"We haven’t made a decision to let it burn itself out, but that may occur before we can safely isolate it," the statement said.
Some residents in Philadelphia said the explosions knocked art off their walls. The blasts were felt as far as South Jersey. The largest blast was so strong that the GOES-16 meteorological satellite recorded it from space.
"I thought it was a meteor or something," a resident who lives next to the complex said after seeing a mushroom-shaped cloud rising from the facility.
Officials have not released details on what caused the explosion. The Chemical Safety Board - an independent, non-regulatory federal agency - said it will deploy a four-person team to investigate the explosion.
The fire was contained shortly before 6 a.m., officials said.
The spokeswoman said PES officials have not determined what product is burning, but said it could be propane. That differs from Philadelphia Fire Department reports.
Deputy Fire Commissioner Craig Murphy said a vat of butane had ignited and eventually exploded. A series of smaller explosions erupted as the fire worked its way through the tangle of pipes carrying fuel across the complex. In all, three explosions took place.
Workers were on site at the time of the explosion, but were far enough away to avoid serious harm, Murphy said. Four refinery staff members suffered minor injuries and were treated at the site, a refinery spokeswoman said.
Large pieces of debris were thrown blocks away and rained down onto streets and traffic lights. A plume of thick, black smoke billowed east from the large complex near Philadelphia International Airport and over portions of South Philadelphia, the Delaware River and into South Jersey.
The smoke could be dangerous, according to Peter DeCarlo, a Drexel University professor and air-quality expert.
"Immediate exposure can trigger asthma and other issues," he cautioned. "If it were me, what I would do is leave the area for as much of the day as possible."
The Philadelphia Department of Health, however, said that they measured the air and has "no findings that would point to any immediate danger in the surrounding community at this time."
The Philadelphia Energy Solutions refinery is the largest single source of particulate pollution in the Philadelphia area even when there isn't an emergency.
The commercial refining complex, which came out of bankruptcy last August, is the largest refinery on the East Coast and employs about 1,000 people. Many Philadelphians still call it the Sunoco refinery, though it is now owned by Philadelphia Energy Solutions, a partnership that includes Sunoco. The Carlyle Group owns 10% of the facility and Energy Transfer Partner has an 8% stake, sources told CNBC.
The refinery processes 335,000 barrels of crude oil every day at two plants in the complex — Girard Point and Point Breeze. The fire broke out at the Girard Point portion. Gasoline, diesel, jet fuel and petrochemicals are also produced at the plant.
The refinery dates back to the 19th Century, opening a year after the Civil War ended.
"The PES Philadelphia Refining Complex has been “part of the neighborhood” in South Philadelphia for over 150 years and is closely tied to the growth of the American oil industry in the 19th century," PES says on its website.
Pictures: South Philadelphia Refinery Explosion and Fire
Friday's fire comes nearly two weeks after another incident at the same complex. On June 10, a small fire broke out at the facility. No one was hurt, but it reignited protests by a group of environmentalists and community members who were concerned about the plant's safety.
Another fire broke out at the complex in 2015.
In its statement, PES said it is "thankful that no one was seriously injured."
"We sincerely apologize for any concern this has caused the community. Concerned residents can call our Community Information Hotline at 215-339-7300 for updates and the status of the refining complex."