An elevated section of Interstate 95 collapsed early on Sunday in Philadelphia after a tanker truck carrying flammable cargo caught fire, closing a heavily traveled segment of the East Coast’s main north-south highway indefinitely.

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 of gasoline. The fire took about an hour to get under control.