Horror inferno kills multiple motorists in US

There's been a massive inferno on a highway in the US after almost 30 vehicles were caught up in a crash.

A truck driver has been charged with causing the pile-up which killed four people and left others with numerous injuries.

The conflagration began when an out-of-control truck raced down a hill towards a traffic jam near Denver on Thursday (local time). One witness says he could have been travelling at almost 130km/h.

"All the cars were stopped; it was a traffic jam. And then this semi-truck... sped by, going... it must have been over 60 miles per hour, 80 miles per hour, out of control down the emergency lane," witness Joshua McCutchen told the Washington Post.

The track smashed into the helpless line of traffic, "causing a very big chain-reaction crash that ignited and started a fire," police spokesman Ty Countryman told media.

At least 28 vehicles were destroyed in the crash and subsequent fire. The inferno was so intense it destroyed the asphalt on the road and melted metal, leaving the stretch of highway engulfed in an apocalyptic blaze.

Some bodies were still trapped amidst the smouldering wreckage hours later, Countryman said, labeling it a scene of "unbelievable" carnage.

The driver of the truck, 23-year-old Rogel Lazaro Aguilera-Mederos, was taken into police custody and charged with multiple counts of vehicular homicide.

Investigators are still working out the cause of the crash.

Newshub.