MILAN — A tanker truck carrying flammable material exploded Monday on a highway near the northern Italian city of Bologna, killing at least two people and injuring up to 70 as a section of the thoroughfare collapsed, the police said.

The Italian police said 60 to 70 people were injured, some with severe burns, during the midday accident on the raised highway north of the city. The Carabinieri paramilitary police said some officers were injured by flying glass when windows in a nearby barracks burst.

Officials said they did not know yet what was in the truck’s tanks, but Italian news agency ANSA reported that the truck was carrying liquefied petroleum gas.

Videos of the blast site showed flames shooting up in the air, followed by a thick cloud of black smoke. Aerial photos showed a gaping hole in the highway next to the tanker.