A major explosion rocked Philadelphia on the morning of June 21, triggering a major fire at an oil refinery in the southern part of the city.
The Philadelphia Office of Emergency Management was asking people to shelter-in-place if they were near the refinery, due to "smoke and apparatus in the area."
The shelter-in-place zone was later narrowed.
The blast took place at about 3:20 a.m. at the Philadelphia Energy Solutions refining complex and the city's fire department rushed to respond.
According to the broadcaster, "The complex 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 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," it added.
Social media users posted their reactions as well as pictures and videos. One posted a video of a fireball erupting into the air, writing: "Just witnessed this explosion heading to Philly airport.. praying no one was hurt."
Another user posted a video about an hour later, saying he'd just landed in the city.
The video showed fires in several different areas.
The Platt Bridge and the Schuylkill Expressway were both re-opened after being closed earlier in the morning.
No injuries had been reported.
The shelter-in-place zone as of 6:15 a.m. was: 26th Street to the west, Schuylkill Expressway to the north, I-95 to the south, and 22nd Street to the east due to smoke and apparatus in the area.