By Ruth Comerford for BBC News
The so-called "super fog," which US media reported was caused by a mixture of marsh fires and dense fog, led to a massive pileup on Interstate 55, about 48km outside of New Orleans, the Louisiana State Police said. Photo: AFP
At least seven people have died after a dense "super fog" caused a huge, 158-car pile-up near New Orleans.
Thick fog and smoke from multiple marsh fires mingled to reduce visibility for drivers commuting on Monday.
Twenty-five people were injured in the crash on Interstate 55 in St John the Baptist Parish, said police, who warned the death toll could rise.
Some vehicles caught fire and were abandoned, leaving a trail of burnt-out wreckage and mangled metal.
The blaze broke out as one of the vehicles involved in the crash was a tanker truck carrying what police called a "hazardous liquid".
One car was driven off the road and into the water, but the driver was safely rescued, police told WWL-TV.
Officers said the motorway will remain closed until at least midday on Tuesday (local time).
"A portion of the crash scene caught on fire shortly after the initial incident. One tanker truck carrying a hazardous liquid is being off-loaded due to a compromised tank/trailer," lieutenant Melissa Matey said in a statement.
Mike Tregre, sheriff of St John the Baptist, said an estimated 100 people were stranded and school buses were being used to transport them to their destinations.
Clarencia Patterson Reed, 46, who was driving to Hammond, told local media she was able to avoid hitting the car in front of her, but the vehicles behind her began slamming into her car.
"It was 'Boom. Boom.' All you kept hearing was crashing for at least 30 minutes," she said.
She was able to get out of her car, but her wife was trapped inside and was injured.
Police are warning the death toll could rise. Photo: AFP
The National Weather Service (NWS) in New Orleans described the weather phenomenon as a "super fog", cautioning that similarly dangerous weather conditions could appear later this week.
On its website, it states super fog can form when a mixture of smoke and moisture from damp, smouldering vegetation mixes with cooler air. The smoky conditions reduced visibility to less than three metres.
The NWS said on Tuesday morning that heavy overnight winds had helped to disperse fog in some areas, but warned that dangerous driving conditions persisted in many areas.
Governor John Bel Edwards offered his thoughts and prayers for those killed in the crash, and urged residents to donate blood at a local medical centre to "help replenish supplies that are being drained today to care for the wounded".
Louisiana has battled blazing wildfires, heatwaves and relentless droughts over the course of the summer. Exceptional drought - the highest category tracked by the US Drought Monitor - is currently in place across 62 percent of the southern state.
- This story was first published bythe BBC.