ROME - At least one person died and more than 60 others were injured Monday when a fireball engulfed a motorway in the northern Italian city of Bologna after a tanker truck carrying flammable materials exploded upon crashing into a lorry.

The blast, which occurred near the area of Borgo Paginale in the west of the city, close to Bologna airport, created a huge hole in the flyover where the explosion took place - causing it to collapse onto another road below - and filling the area with flames and black smoke.

A video released by the police shows the moment the tanker ploughs into the back of the lorry, immediately catching fire as another lorry crashes into the back of the blazing tanker and oncoming traffic screeches to a halt.

The three vehicles, invisible due to the pulsing smoke, were then reduced to little more than ash by a massive explosion that swept across the motorway and could be heard throughout the city.

“I was here (at a nearby restaurant) for work... at a certain point we heard a violent blast, i thought it was a terrorist attack,” Marco Rosadini, whose car is trapped under the flyover, told the daily La Repubblica.

“After the explosion the roof of the restaurant started to collapse. I looked outside and I felt like I was looking at a wall of fire.”

Images released earlier by the fire service showed burning cars in an adjacent carpark.

Italian media quoted the Bologna prefecture as saying that two people had been killed, but when asked for confirmation by AFP, a spokeswoman said that the official toll remained one dead, with 68 injured.

However, the Italian fire service told AFP that the number of dead is likely to rise.