Authorities in the northeastern US city of Philadelphia, Pennsylvania, said the collapse of an elevated section of the Interstate-95 (I-95) freeway on Sunday morning was caused when a truck burst into flames underneath it.
No injuries have been reported in the incident but the damage will likely close one of the country's busiest highways for weeks, if not months.
"Companies arrived on location and they found... heavy fire from a vehicle — we don't know what type of vehicle it was," said Captain Derrick Bowmer of the Philadelphia Fire Department. Early reports suggested the vehicle that caused the damage was a fuel tanker truck but authorities would not confirm or deny the claim.
A city spokesperson simply noted that a "large fire" had caused the damage, with no mention of a vehicle.
The US National Transportation Safety Board (NTSB) said later on Sunday that it was dispatching a team to investigate what it called a gasoline tanker truck fire and the collapse of the overpass.
How did the I-95 overpass collapse?
The fire severely weakened a four-lane northbound overpass, causing a large section of it to collapse. Authorities say they are looking for the driver of the suspected vehicle, who was no longer at the scene when they arrived.
Bowmer said his department is treating the situation as a hazardous materials — or hazmat — incident.
Residents in the northeastern Philadelphia neighborhood of Tacony reported hearing several explosions after the original accident. Fire Department officials say these may have been caused by gas runoff from the crash, or exploding underground gas mains.
Beyond caustic smoke from the flames of the fire, authorities fear toxic materials may leach into the ground as well as the adjacent Delaware River, causing further environmental damage still.
How long will I-95 be closed?
Heavily traveled, I-95 is a major north-south thoroughfare in the eastern US, connecting cities along the eastern seaboard from Maine to Florida.
Sunday's bridge collapse has now closed it in both directions near Philadelphia and will create traffic backups for commuters and travelers as the US summer travel season kicks off.
"Avoid area. Plan and seek alternative travel routes," read a tweet put out by the Philadelphia Office of Emergency Management.
"I-95 will be impacted for a long time… a long time," said Philadelphia Managing Director Tumar Alexander at a Sunday news conference.
"Today's going to be a long day. And obviously, with 95 northbound gone and southbound questionable, it's going to be even longer than that," said Dominick Mireles, director of Philadelphia's Office of Emergency Management.
US Secretary of Transportation Pete Buttigieg, who said the closure would have "significant impacts" in and around Philadelphia, offered "any assistance that USDOT can provide to help with recovery and reconstruction."
The White House also announced that President Joe Biden had been briefed on the situation and has reached out to state and local officials to offer help.
Thousands of tons of debris will first have to be cleared before authorities will even be able to assess the damage and plan reconstruction to the northbound and possibly the southbound sections of the freeway.
Pennsylvania's Democratic Governor Josh Shapiro said Sunday that repairs would take "several months."
When a similar fire — caused by the illegal burning of tires — damaged a section of I-95 in Philadelphia in 1996, it closed the highway for weeks and prompted partial closures that lasted six months.
(Photo: Twitter/Philadelphia Fire Department)
