Sunday’s fire closed a heavily traveled segment of the East Coast’s main north-south highway indefinitely. Newscasts warned of traffic nightmares and gave advice on detours, urging drivers to take more time to travel.

“This is really going to have a ripple effect throughout the region,” AAA spokesperson Jana Tidwell said Monday. She advised people to avoid peak travel times.

Tidwell also anticipated that drivers will incur additional costs — “more gasoline, more wear and tear on their cars, additional tolls, in terms of leaving Pennsylvania into New Jersey and then back into Pennsylvania.”

The Southeastern Pennsylvania Transportation Authority said it was operating three extra morning and late afternoon trains on its Trenton, New Jersey, line, and adding capacity to regularly scheduled lines during peak hours “to help support the city and region’s travel needs” following the collapse.

Transportation officials warned of extensive delays and street closures and urged drivers to avoid the area in the city’s northeast corner. Officials said the tanker contained a petroleum product that may have been hundreds of gallons (hundreds of liters) of gasoline. The fire took about an hour to get under control.

The northbound lanes of I-95 were gone and the southbound lanes were “compromised” by heat from the fire, said Derek Bowmer, battalion chief of the Philadelphia Fire Department. Runoff from the fire or perhaps broken gas lines caused explosions underground, he added.

Some kind of crash happened on a ramp underneath northbound I-95 around 6:15 a.m., said state Transportation Department spokesman Brad Rudolph, and the northbound section above the fire collapsed quickly. A massive concrete slab fell from I-95 onto the road below.

Gov. Josh Shapiro said his flight over the area showed “just remarkable devastation.”

“I found myself thanking the Lord that no motorists who were on I-95 were injured or died,” he said.

The collapsed section of I-95 was part of a $212 million reconstruction project that wrapped up four years ago, Rudolph said.

Motorists were sent on a 43-mile (69-kilometer) detour Sunday, which was going “better than it would do on a weekday,” Rudolph said. The fact that the collapse happened on a Sunday helped ease congestion.

Pennsylvania Transportation Secretary Michael Carroll said the I-95 segment carries roughly 160,000 vehicles per day and was likely the busiest interstate in Pennsylvania.

Shapiro said he had been spoken directly to U.S. Transportation Secretary Pete Buttigieg and had been assured that there would be “absolutely no delay” in getting federal funds quickly to rebuild what he called a “critical roadway” as safely and efficiently as possible. But Shapiro he said the complete rebuild of I-95 would take “some number of months,” and in the meantime officials were looking at “interim solutions to connect both sides of I-95 to get traffic through the area.”

The National Transportation Safety Board said it was sending a team to investigate the fire and collapse.

Officials were also concerned about the environmental effects of runoff into the nearby Delaware River.

After a sheen was seen in the Delaware River near the collapse site, the Coast Guard deployed a boom to contain the material. Ensign Josh Ledoux said the tanker had a capacity of 8,500 gallons (32,176 liters), but the contents did not appear to be spreading into the environment.

The fire was strikingly similar to another blaze in Philadelphia in March 1996, when an illegal tire dump under I-95 caught fire, melting guard rails and buckling the pavement.

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Associated Press writers Mark Scolforo in Harrisburg, Pennsylvania, Jake Offenhartz in New York, and Kathy McCormack in Concord, New Hampshire, contributed to this report.