A "rotten eggs" smell that slunk across the city Friday night was caused by a chemical release at a South Jersey refinery, officials said Saturday.

Paulsboro Refinery released 130 pounds of sulfur dioxide and nine pounds of hydrogen sulfide Friday night, according to Philadelphia police.

PBF Energy, which runs the refinery, apologized and said Saturday that a brief loss of power at the refinery shortly before 8 p.m. Friday resulted in "flaring and odors." The refinery is located just across the Delaware River.

The odor was not dangerous, officials said, and no injuries were reported.

The release was not at a level high enough to require reporting by the company, said a police spokesperson.

As residents wondered late Friday night what that smell was, a PGW spokesman said there was no elevated levels of natural gas in the atmosphere.

Though it smelled like a sulfur-based additive used to make natural gas identifiable, the spokesman, Barry O'Sullivan, also said it was not that chemical, which is called mercaptan.