Four people have been killed and 13 injured after an avocado truck crashed and burst into flames on a busy Louisiana highway.

Police said the 18-wheeler truck failed to stop as it approached congestion on the I-12 near Covington on Saturday at 4pm and resulted in a pile up with nine other vehicles.

The truck, which was hauling avocados, managed to jackknife during the crash and caught fire before quickly engulfing three other vehicles.

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Police said the 18-wheeler truck failed to stop as it approached congestion on the I-12 near Covington, Louisiana on Saturday at 4pm and resulted in a pile up with nine other vehicles

Mother and son Yoland and Keland Simmons, of Baton Rouge (left), both died at the scene after their 2014 Lexus IS 350 was struck by the truck. Another victim, Rachel Lehmann of Mandeville (right), was taken to hospital where she later died

The 18-wheeler driver died at the scene but police have not yet been able to confirm their identity.

Two other people died at the scene, including mother and son Yoland and Keland Simmons of Baton Rouge - the driver and passenger of a 2014 Lexus IS 350 that was struck by the truck.

A fourth person Rachel Lehmann of Mandeville, who was the driver of a 1997 Toyota 4-Runner, was taken to hospital where she later died.

Several others were taken to local hospitals suffering varying degrees of injuries.

A St Tammany Parish Sheriff's Office deputy was also injured and treated but is expected to make a full recovery.

The truck, which was hauling avocados, managed to jackknife during the crash and caught fire before quickly engulfing three other vehicles, including another 18-wheeler

The crash forced the highway to be shut down for several hours as fire crews battled the blaze

Photos shared by the Louisiana State Police showed the aftermath with piles of ash covering the highway

The crash forced the highway to be shut down for several hours as fire crews battled the blaze.

Photos shared by the Louisiana State Police showed the aftermath with piles of ash covering the highway and the front cab of the trailer completely burned.

'This was a horrific crash. We are praying for all who have been affected by this tragedy and are grateful to the many who have expressed their concern,' the St Tammany Parish Sheriff's Office said.

Investigators say they have not yet determined whether the truck driver was impaired and toxicology results are pending an autopsy.

Authorities are still investigation the crash.

The driver of the 18-wheeler died at the scene along with two other people. A fourth person later died in hospital