A small fire continued to burn Saturday at the East Coast's largest oil refinery a day after explosions and a predawn blaze that shook homes, sent a fireball aloft and caused some minor injuries.
Workers tried to isolate the remaining line feeding the fire at the 150-year-old Philadelphia Energy Solutions refinery in South Philly, but access is limited "due to the damage and instability of the remaining structure," a PES spokeswoman said.
Officials haven't decided whether to let fire burn itself out, "but that may occur before we can safely isolate it," the spokeswoman said.
"Managing the small existing fire in this manner is safest for the environment, (company) employees, and the surrounding community to bring the incident to a safe conclusion," the company said in a statement.
Earlier in the day, Philadelphia Mayor Jim Kenney told reporters he was shocked after learning about the explosions.
"My initial reaction was 'Damn, this is bad,'" Kenney said. "It was a frightening scene. I'm thankful that no one got killed or seriously injured.”
Four refinery staff members suffered minor injuries and were treated at the site, a refinery spokeswoman said. A shelter-in-place order was also briefly issued Friday morning after the fire broke out around 4 a.m.
PES officials remained at the refinery Saturday, in addition to personnel from both the Philadelphia Fire Department and Office of Emergency Management.
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.
Kenney said that city agencies would continue to monitor the situation and air quality.
Late Friday, City Councilmember-at-Large Helen Gym called for the closure of the refinery until PES could assure the safety of its workers and neighboring residents.
Kenney said health and safety issues need to be addressed, but he stopped short of calling for the closure of the plant.
"We will see what the federal and state authorities say, if that's what is called for that's what we will do," Kenney said.
Officials have not released details on what caused the explosion.
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.
The Chemical Safety Board — an independent, non-regulatory federal agency — said it will deploy a four-person team Monday to investigate the explosions and fire.
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 discovered "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 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.
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."