A large fire broke out early Friday at an oil refinery in Philadelphia, rattling the area with at least one booming explosion and lighting up the dark sky with huge balls of gas and flame.
The explosion and fire came from a vat of butane -- one of the products that come from the process of refining crude oil -- at the Philadelphia Energy Solutions refinery starting around 4 a.m., city Deputy Fire Commissioner Craig Murphy said.
The refinery's fire crews have been fighting the flames -- with city fire crews in support -- and the blaze has been contained to the general vat area, Murphy said.
"The fire is not under control yet. Right now, companies are making sure that the fire does not spread," Murphy told reporters after dawn.
By 7 a.m., the flames were significantly lower, video from CNN affiliate WPVI showed -- a stark contrast to the massive fireball that bystanders recorded on social media earlier in the morning.
One worker complained of chest pains after the fire started but did not need to be taken to a hospital, Murphy said, and no other injuries have been reported.
Details about what started the fire weren't immediately available. Authorities are working to account for all of the personnel, Philadelphia Energy Solutions spokeswoman Cherice Corley said -- though Murphy said no one who'd been at the facility is missing.
Employees "were working somewhere close to the vat" when the fire started, "but far enough away that the initial explosion didn't injure anyone," Murphy said. He said he didn't know what work was being done.
Residents reported several explosions that were felt in South Jersey and Delaware County, Pennsylvania, according to WPVI.
Small fires were burning near the vat as well, Murphy said. The extent of damage to the refinery wasn't clear early Friday, but it appeared to be confined to the vat area. Tanks surrounding the area are being cooled as a precaution, he said.
Emergency management officials initially asked people east of the fire to shelter in place, but by 7 a.m., that order was being lifted, Murphy said.
Philadelphia Energy Solutions had an industrial hygienist take air-quality readings, and the area "is clear," Murphy said. The company will continue to monitor the air in neighborhoods to the east.
"The shelter in place (order), which was lifted, was precautionary due to smoke plume. Philadelphia Energy Solutions ... report no detectable inhalants," the city fire department said on Twitter.
Portions of Interstate 76 and the city's Platt Bridge were temporarily closed after the fire, according to the city's Office of Emergency Management.
The facility -- in the south of the city, a few miles from Philadelphia International Airport -- is the largest oil refining complex on the Eastern Seaboard, according to its website. Philadelphia Energy Solutions employs more than 1,000 people and refines 335,000 barrels of crude oil a day.