A stream winding through a populous area on the outskirts of Buenos Aires has turned crimson red in recent hours, sparking fears of industrial chemical dumping, images shared by residents on social media showed Friday.

A stream south of the Argentine capital turned a freakish vermilion this week, prompting concerns about pollution. Officials said it could be the result of “some type of organic dye.”

This water is raising a red flag. A canal in Argentina mysteriously turned bright red on Thursday, alarming residents who were woken up by its strong odor. “The smell woke us up. In the daytime, when we looked at this side of the river,