At least two people died and up to 70 were injured Monday when a truck exploded in Bologna, Italy.

A fuel tanker collided with another truck carrying vehicles on the A14 highway near the airport, sparking a fireball and plume of smoke was visible for kilometres.

Police said the tanker truck failed to brake when encountering heavy traffic and smashed into the back of a truck that was stopped, and that a third vehicle may have hit the tanker truck from behind.

The fire started soon afterward, and many drivers were able to get away from the flames before the tanker truck exploded.

Photos from the scene show that several lanes of the highway have collapsed, while the flames also spread to several cars parked under and adjacent to the highway at a Peugot dealership, sending more plumes of black smoke into the air.

A woman living a kilometre from the blast site said many residents had to leave due to the black smoke.

"I was in the house and I heard a huge bang and screams from the window. I saw a huge plume of smoke," Crisina Felicani told Sky TG24. "There was panic in the neighbourhood, because it wasn't clear what happened."

Italian media reports that some people were injured by glass flying from windows shattered by the force of the explosion.

Firefighting crews used a helicopter to haul water from the Rhine river to drop onto the flames.

Police said : "Due to an accident on the highway, an explosion occurred resulting in a fire at Via Marco Emilio Lepido. Circulation compromised, not only on the motorway, but also in the Borgo Panigale area."