At least 56 people have been injured after a major explosion left a bridge partially collapsed on a highway near Bologna in Italy.

Italian news agency ANSA reported that the explosion was caused by an accident involving a truck that was transporting flammable substances, which exploded upon impact.

Italy's firefighters tweeted that they have sent multiple rescue and emergency squads, including one from their urban search and rescue team.

Italian news channel Sky TG24 reported that some of the injured people had been hit by flying glass when windows in nearby buildings exploded.