Updated

A utility company says a transformer issue is to blame for causing white foam to seep out of a downtown Philadelphia substation and onto a side street this past weekend.

PECO Energy Co. spokesman Ben Armstrong dispelled rumors Monday that an explosion occurred at the substation Saturday afternoon.

The frothy mess can be traced back to one of the site's transformers, which flashed momentarily and shut down with an audible popping sound when a circuit breaker went offline.

Armstrong says the outage triggered emergency systems to flood the substation with fire-suppressing foam. Approximately 2,700 PECO customers briefly lost power.

A hazmat crew was able to clean up the foam, which isn't toxic, after a few hours.

An internal investigation is ongoing.