An orange fireball filled the sky in Philadelphia early Friday after an explosion at an oil refinery in the southwest part of the city.

From Pennsylvania to New Jersey, there were reports of homes shaking, as people awoke to a smoke-filled sky and orders to shelter in place.

No significant injuries were reported, according to the Philadelphia Fire Department, which was working to put out the fire Friday morning.

Firefighters responded to a report of an explosion around 4 a.m. at Philadelphia Energy Solutions, a refining complex near the Schuylkill between the city’s international airport and downtown. The complex includes two refineries, which together can process about 335,000 barrels of crude oil per day. It is the largest oil refining complex on the Eastern Seaboard, according to the company.