The accident, involving three cars, happened near Lodi in the early hours of Thursday morning when a car hit the boars as they crossed the motorway, which connects Milan and Naples, Italian media reports.
A second vehicle crashed into the car from behind, and a third car then hit one of the drivers who had climbed out of their vehicle.
A 28-year-old man died at the scene, while his 27-year-old girlfriend, in a serious condition, was taken to hospital along with other victims. Five of those injured were children, aged between eight and 15.
Three wild boars were killed in the accident. Authorities believe they had dug a hole beneath the fence that runs alongside the motorway.
Italy has a large wild boar population, and it’s not unusual for them to be hit by vehicles after straying onto roads. However, such serious accidents are not common.
Hundreds of thousands of wild boar live in the forests of north and central Italy. File photo: Depositphotos.
In Lombardy alone, there have been around 400 road accidents involving the animals in the last five years, according to agricultural association Coldiretti.
The number of wild boars in Italy has almost doubled in the last ten years, and “the presence of wild boars in population centres and on roads is now a real risk for the safety of citizens," Coldiretti says.
Lombardy Agriculture Councilor, Fabio Rolfi, said such accidents “could be avoided” and said hunters should be employed to cull the number of wild boars in the region.
In 2015, the deaths of two Italians in separate road collisions with the animals, in Tuscany and Abruzzo, prompted calls for a cull.
Attempts to control their reproduction through birth control tablets were trialled in Tuscany in 2015, but it seems that the boar population is continuing to increase, both in rural and urban areas.