Two trucks collided on a motorway near Bologna airport in northern Italy, sending a huge ball of fire and billows of black smoke soaring into the sky.
At least two people have been killed and more than 60 injured in Monday's crash, according to local media.
Police said they 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.
Firefighters and ambulances headed to the scene.
A video shot from a parked car at the moment of the explosion appeared to show someone being engulfed by flames when the tanker exploded.
In a separate incident on Monday, 12 migrant labourers died in the southern Italian region of Puglia when the van they were travelling in smashed into a lorry.