A fiery motorway crash in northern Italy has killed six people, according to reports.

RAI state TV quoted firefighters in Brescia as saying that five of the dead, including two children, were in a car, and the sixth victim was a truck driver.

RAI said traffic on the A21 route had already slowed to a crawl because of an earlier accident when a truck loaded with sand struck the car in front of it, which in turn slammed into a tanker truck whose flammable liquid cargo caught fire.

Authorities did not immediately identify the liquid.

Firefighters were on the highway about a mile north of the scene dealing with the earlier accident when the tanker caught fire.

Thick, dark smoke was visible for miles.