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

Twenty-five people were injured and the number of fatalities may increase as first responders continue to clear the crash scenes and search for victims, Louisiana State Police said in a press release Monday evening.

Gov. John Bel Edwards issued a call for blood donors and asked for prayers “for those hurt and killed.”

Videos of the wreck showed what looked like an endless junkyard of cars overtaking the busy interstate near the community of Manchac. Vehicles were crushed, rammed under one another and some were engulfed by flames. Many people stood on the side of the road looking in disbelief at the disastrous scene, while others remained in their car waiting for aid.

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 other drivers calling for help and 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 Times-Picayune/The New Orleans Advocate said 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.

Louisiana State Police shared aerial photos on their Facebook page showing dozens of 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.

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.