Explosion rocks South Philadelphia oil refinery

An explosion struck a South Philadelphia oil refinery early Friday morning.

According to Fox29, the Philadelphia Energy Solutions oil refinery, near one of the city's sports complexes, experienced a massive explosion.

Photos and videos published on social media show the facility engulfed by a massive fireball – reported as a 3-alarm fire by local reports.

The refinery, established in the post-Civil War era, was once Philadelphia's biggest employer, according to reporter Steve Keely.

There were no immediate reports on possible fatalities or injuries.

This is a developing story. Check back for updates.