By Ray Boyd

PHILADELPHIA (CBS) — On Thursday night, Philadelphia Fire Department officials responded to the Schuylkill River for a hazardous material situation. Authorities were on the scene around 6:46 p.m.

A slight green sheen appeared in the river, according to officials.

They say it was an oily substance in the water and that it smelled like diesel fuel. Crews are investigating what the substance is and how it wound up in the river.

This is the second time this week that crews have been out to the Schuylkill River for a similar situation. On Monday, crews were on the scene at the river looking into an oil spill. Oil could be scene in the river spanning from Chestnut Street to South Street.