Interstate 95 collapse repairs to take 'months' in Philadelphia ...

Repairs on Interstate 95 are expected to take "months" after an elevated section collapsed in Philadelphia on Sunday morning when a tanker truck carrying flammable cargo caught fire beneath the overpass, officials said.

"With regards to the complete rebuild of I-95 roadway, we expect it to take some number of months," Pennsylvania Gov. Josh Shapiro told a press conference on Sunday evening, adding that he plans to issue a disaster declaration to "expedite this process" and "immediately draw down federal funds."

Shapiro said he had spoken directly to Secretary of Transportation Pete Buttigieg who assured him there would be "absolutely no delay" in getting federal funds to safely and swiftly rebuild the "critical roadway."

In the meantime, officials are looking at "interim solutions to connect both sides of I-95 to get traffic through the area," according to Shapiro. All lanes between the exits for Philadelphia's Woodhaven Road and Aramingo Avenue are closed in both directions indefinitely, local ABC station WPVI reported.

The northbound side of the affected segment "completely collapsed," while the southbound lanes are "not structurally sound to carry any traffic," Shapiro said. One vehicle remains trapped beneath the collapsed roadway, according to the governor.

"We are still working to identify any individual or individuals who may have been caught in the fire and the collapse," he said, before later clarifying that no one on I-95 at the time was injured or killed in the incident.

Inspectors from the Pennsylvania Department of Transportation determined that the southbound portion cannot be reopened and will also need to be replaced, according to a U.S. Department of Homeland Security report reviewed by ABC News on Monday.

The report said the deck of the collapsed overpass is no longer sound, though inspections remain ongoing. Gasoline from the tanker truck has flowed into storm drains and a sheen was spotted on the water of a nearby cove of the Delaware River, which flows for 282 miles along the borders of New York, Pennsylvania, New Jersey and Delaware. The U.S. Coast Guard is at the scene and will continue to work with the Philadelphia Water Department to detect any other potential environmental impacts of the fire on the major waterway, according to the report.

The tanker truck was transporting 8,500 gallons of gasoline at the time, according to Coast Guard petty officer Kimberly Reaves.

I-95 is one of the busiest travel corridors in the United States and serves as the main north-south highway on the East Coast. An average of more than 160,000 vehicles travel across the impacted section in Philadelphia every day, according to a spokesperson for the Pennsylvania Department of Transportation.

President Joe Biden has been briefed on the collapse and his administration is in communication with Shapiro as well as Philadelphia Mayor Jim Kenney, according to White House press secretary Karine Jean-Pierre.

Federal Highway Administrator Shailen Bhatt will travel to Philadelphia on Monday to offer federal support and assistance.

A team of specialists from the National Transportation Safety Board, in coordination with the Pennsylvania State Police, will also be on site Monday to begin the on-scene portion of their safety investigation into the incident. A preliminary report will be available in two to three weeks, according to the NTSB.

ABC News' Victoria Arancio, Matt Foster, Amanda Maile and Josh Margolin contributed to this report.