Officials are scrambling to set up alternate transportation options for Monday morning commuters after a section of Interstate 95 collapsed in Philadelphia due to a tanker truck fire Sunday -- leaving the East Coast's primary highway with major damage that could take months to repair.

No injuries or fatalities from the highway collapse have been reported. But it remained unclear whether anyone was caught in the burning commercial tanker truck, which was carrying a flammable substance/oil?. The truck was still trapped under the collapsed highway Sunday afternoon, Pennsylvania Gov. Josh Shapiro said at a news conference.

Roughly 160,000 vehicles typically commute on the now-collapsed road each day, making it "likely the busiest interstate in our commonwealth," said Pennsylvania Department of Transportation Secretary Mike Carroll.

"I found myself thanking the Lord that no motorists who were on I-95 were injured or died," Shapiro said, describing witnessing "remarkable devastation" during a flyover of the scene.

Northbound lanes collapsed and southbound lanes were damaged due to the intensity of the blaze and were "not structurally sound to carry any traffic," Shapiro said. Restoring the highway will likely take months, he said, adding that his office was looking into "alternatives to connect the roadway beyond detours."

Rep. Brendan Boyle, a Democrat whose district includes the section of the highway, told CNN that "you are literally going to have millions of people in what is one of the largest population centers in the country impacted in a significant way."

The governor said he plans to issue a disaster declaration Monday, allowing the state to immediately dip into federal funds, cut through the red tape and move quickly to repair and reconstruct this roadway. He said he got assurances from Transportation Secretary Pete Buttigieg.

"Secretary Buttigieg has assured me that there will be absolutely no delay in getting federal funds deployed to quickly help us rebuild this critical artery. I-95, of course, is a critical roadway that supports our economy and plays an important role in folks everyday lives," Shapiro said.

The commercial tanker truck, which was carrying a petroleum-based product, caught fire around 6:20 am ET, causing a section of the overhead northbound I-95 highway to collapse atop the truck, authorities said. The cause of the fire is also under investigation.

By Sunday afternoon, the fire was contained but firefighters remained at the scene as a precaution "because of the large volume of product that was involved," Philadelphia Fire Department Deputy Commissioner Jeffrey Thompson said.

Crews will be working through the night to clear the collapsed section of the road, Carroll said.

Officials warned residents to avoid the area and to expect delays of trash collection and bus routes in the area.

"The challenges will be real when it comes to traffic movements in the city as a result of this incident," Carroll said.

Leslie Richards, general manager of the Southeastern Pennsylvania Transportation Authority (SEPTA), said the agency is adding extra capacity and service to other transportation routes and evaluating all options in assisting travelers work around the highway collapse including.

"In order to accommodate travel through the city and region following the I-95 collapse, SEPTA will provide added capacity and Service. on the Trenton, West Trenton and Fox Chase Lines," SEPTA, the sixth largest public transportation agency in the US, said in a statement.

Video shows 'dip' in the road before collapse

Mark Fusetti was driving south on I-95 in Philadelphia to pick up his son from the airport on Sunday before the collapse when he saw large plumes of dark smoke and began filming, initially thinking there was a brush fire.

Video he filmed on his cellphone appears to show his car and other vehicles driving over a "dip" along I-95 as smoke billowed from under both sides of the highway. He said he was startled by the dip, saying, "it felt like you drove off a curb."

"I realized what happened when I looked in my rear-view mirror. I see 95 -- all of the cars stopping and then I learned, shortly after that the road had just collapsed and what was really going on," Fusetti told CNN's Jim Acosta Sunday.

The cause of and circumstances surrounding the fire and collapse remain under investigation, officials say.

Philadelphia Fire Department Battalion Chief Derek Bowmer said "it looked like we had a lot of heat and heavy fire underneath the underpass."

With thousands of tons of steel and concrete on top of where the fire was burning, firefighters initially faced a challenge getting to the seat of the fire, Bowmer said during a news conference Sunday morning.

There were also explosions around the highway collapse caused by "runoff of maybe some fuel or gas lines that could have been compromised by the accident," Bowmer noted.

"We have fire coming out of those manholes," Bowmer said Sunday morning.

While the exact cost of repairing the crucial roadway remains unclear, the governor told reporters Sunday afternoon that the state is working with federal officials on a "speedy rebuild of I-95."

President Joe Biden has been briefed on the collapse, according to a tweet from White House press secretary Karine Jean-Pierre.

A spokesperson for the Federal Highway Administration said administrator Shailen Bhatt would be in Philadelphia on Monday to "offer federal support and assistance."

Coast Guard reports 'sheen on the water' after collapse

The US Coast Guard, which was looking out for possible water pollution after the fire and road collapse, reported "a sheen on the water" that was confined to one area, according to a spokesperson.

The tanker that caught fire has the potential to spill 8,500 gallons of gasoline, the Coast Guard said in a statement.

A 29-foot boat was sent to monitor the area "to observe any pollution to the waterways. They reported that there is a sheen on the water but it seems to be confined to the cove," the Coast Guard's statement reads. "The substance is gasoline and the tanker has a potential to spill 8500 gallons. However, it has been reported to us that clean up efforts are mainly shore side, meaning on land."

The governor later Sunday sought to assure residents, saying "there is no threat to anyone's drinking water."

Brendan Riley, director of water operations for the Philadelphia Water Department, echoed that water in the city was safe.

"At this point in time, we have no concerns of any environmental impact to our water intake at the Baxter Water treatment plant," Riley said. "There was a lot of coordination with the Department of Environmental Protection, the US Coast Guard as well as to make sure that we responded appropriately and deploy some booms, not only at our intakes but also at the outfall location where there was any potential discharge."