Lawrence Township Fire Marshal Dick Groves says the "humungous" explosion happened Thursday on a ramp from I-69 to I-465 on the city's northeast side.
He says the fireball could be seen and the heat felt from two miles away.
Groves says the truck driver was taken to a hospital with burns that didn't appear life threatening and at least one other driver was taken to a hospital.
Groves says the truck rolled, with the cab and tanker separating and catching fire underneath I-465.
State Police Sgt. Anthony Emery says traffic on I-465 near the explosion scene will be closed until the bridge is tested for safety.
The Associated Press