NEW ORLEANS — At least seven people were killed Monday morning after a “superfog” of smoke from south Louisiana marsh fires and dense fog caused multiple massive car crashes involving 158 vehicles, authorities said.

Twenty-five people were injured and the number of fatalities may increase as first responders work into the night clearing the scenes and searching for victims, Louisiana State Police said in a statement Monday evening.

Videos of apocalyptic type scenes from the aftermath of the wrecks showed a long stretch of mangled and scorched cars on Interstate 55 near New Orleans. Vehicles were crushed, rammed under one another and some engulfed by flames. Many people initially stood on the side of the road or on the roof of their vehicle looking in disbelief at the disaster, while others cried out for help.

Piles of disformed cars, heaped on top of one another as firefighters trudged through the debris, remained on the interstate as the sun set. Hours after the crashes, the smell of burnt wreckage still wafted in the area.

Christopher Coll, 41, was among the drivers in one of the pileups.

“I was already on the brakes, slowing down when an F-250 drove up on top of my work trailer and took me for a ride,” Coll told The Times-Picayune/The New Orleans Advocate.

Coll could smell smoke as he heard the sounds of crashing cars and popping tires. He was able to kick open his passenger door to escape and then helped others – pulling out one person through a car window.

Clarencia Patterson Reed was also in the wave of wrecked cars as she drove to Manchac with her wife and niece. Reed told the newspaper that she could see people waving their hands for her to stop, but when she did her car was hit from behind and on the side by two other vehicles.

“It was ‘Boom. Boom.’ All you kept hearing was crashing for at least 30 minutes,” Reed said. She was able to scramble out of her car, but her wife was pinned inside and injured her leg and side.

While 25 people were transported to the hospital, with injuries ranging from minor to critical, many others sought medical aid on their own, authorities said.

Gov. John Bel Edwards asked for prayers “for those hurt and killed” on Monday and issued a call for blood donors to replenish dwindling supplies.

Louisiana State Police shared aerial photos on their Facebook page showing the crashed cars and extensive debris on both northbound and southbound lanes of the elevated interstate, which passes over swamp and open waters between lakes Pontchartrain and Maurepas.

As of Monday afternoon, state troopers were still working “to notify families, investigate the exact causes of the crashes” and coordinate with the state’s transportation department to have the bridge inspected.

Traffic backed up for miles in both directions on I-55. The lack of visibility also prompted closures of parts of I-10 and the 24-mile (39-kilometer) Lake Pontchartrain Causeway at times.

School buses were summoned to transport stranded motorists from the accident sites. At midday, state police told reporters at the scene that one vehicle went over the highway guardrail and into the water, but the driver escaped unharmed.

A tanker truck, which was carrying a hazardous liquid, is having to be off-loaded from the crash site. Once the truck is removed, officials said that first responders will be able to better assess the scene.

On social media, the National Weather Service said there were multiple wetland fires in the region. Smoke from the fires mixed with fog to create a “superfog.” Visibility improved as the fog lifted, according to the agency. But it was unclear how long the marsh fires, smoke from which could be seen and smelled in the New Orleans area over the weekend, would be a factor.

The Times-Picayune/The New Orleans Advocate reported several schools in and near New Orleans announced class cancellations or delayed openings due to the smoke and fog. Smoke from the Bayou Sauvage Urban National Wildlife Refuge was thick enough that the city announced locations where free masks could be picked up in eastern New Orleans and in the Algiers neighborhood on the west bank of the Mississippi River.