New Orleans, Louisiana - At least seven people have been killed in a freeway pileup involving 158 vehicles caused by dense "superfog" in Louisiana on Monday.

At least another 25 people were injured, some of them seriously. The injured were taken to hospitals after the pile-up west of New Orleans, the state police said. It was possible that more fatalities would be found.

Part of the accident scene on US Interstate 55 was engulfed in flames after a tanker loaded with a hazardous liquid caught fire.

Police released photos showing a debris field of destroyed and mangled cars on both sides of the road.

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Meteorologists said that a "superfog" had severely impaired visibility between Ruddock and Manchac parishes on Monday morning at the time of the pile-ups, according to CNN.

The "incredibly dense fog" was caused by a combination of fog and smoke from nearby fires, according to the National Weather Service (NWS). The "superfog" is a particularly dense fog that develops in humid, smoky conditions and can cause visibility to drop to less than 10 feet, the NWS said.

Louisiana has been battling unprecedented wildfires, extreme heat, and severe drought since the summer. CNN reported that 62% of the state is experiencing exceptional drought, the highest category.

The city of New Orleans said the lack of rain combined with the summer's extreme heat had dried up wetlands and lowered groundwater levels.