A dangerously thick “superfog” that caused a huge vehicle pileup north of New Orleans on Monday was made worse by wildfires burning nearby, according to local officials. Seven people were killed and more than two dozen others were injured in crashes involving at least 158 vehicles in the northbound and southbound lanes along a stretch of Louisiana’s Interstate 55. An unusually dense layer of fog was partly to blame for the accidents, which left a mileslong trail of crumpled and charred vehicles.
The superfog in Louisiana was the thickest early Monday and had mostly lifted by that afternoon, though fog advisories remained over a small patch of the state into Tuesday. Superfog conditions are unusual but do occur periodically in the South, where marsh fires, calm winds and humidity can combine to create thick veils of fog. Multiple marsh fires have been burning in the area, according to the New Orleans branch of the weather service.