Photos on social media showed a huge ball of fire and black smoke billowing into the sky at the scene of the crash.
Rome: Two trucks collided on a motorway near Bologna airport in northern Italy on Monday, sending a huge ball of fire and billows of black smoke soaring into the sky.
At least two people were killed and more than 60 were injured, according to local media.
Police said they had closed off the road where the crash took place as well as the surrounding area in Borgo Panigale, on the outskirts of Bologna.
Italian media said a lorry carrying cars collided on a bridge with another tanker lorry containing inflammable materials.
Part of the bridge collapsed and the resulting explosion and fire spread to a carpark below the bridge, where several other vehicles caught fire and exploded.
The explosion occurred near Borgo Paginale to west of the city, very close to Bologna airport, at around 2:00 pm (1200 GMT), the Italian fire service said on Twitter.
The cause of the blast is not yet known.
A video published on Twitter by the Italian fire service shows a huge column of black smoke billowing from the wreckage of the truck on the city's ring road. Images released earlier by the fire service showed burning cars in an adjacent car park.
One video filmed by a motorist circulating on Twitter shows the moment the tanker exploded, when a black plume of smoke was suddenly swept away by a powerful ball of flame that takes over the entire horizon.