A series of crashes have occurred on a major expressway in southern Vietnam on Tuesday afternoon, as an enormous cloud of thick smoke shrouded a portion of the freeway.

A number of vehicles slammed into each other due to the obstructed view while travelling on the Ho Chi Minh City-Long Thanh-Dau Giay Expressway, which stretches 55 kilometers from the metropolis to Dong Nai Province, at around 3:00 pm.

In a video published on Facebook by witnesses, several drivers were making phone calls for an ambulance in panic, saying many people had been wounded.

The drivers baulked at running to the rescue of those who were still trapped in the smoke-cloaked area, fearing that they would cause more accidents due to the poor visibility.

The smoke was supposed to arise after farmers burned straw left in paddy fields after a harvest.

At 3:45 pm, in the section of the freeway leading to Ho Chi Minh City, three vehicles were reported to be damaged as they were rear-ended, and the traffic has returned to normal as traffic police were present at the scene.

However, in the other direction leading to Long Thanh, six vehicles were damaged, with one of them in a serious condition, and several of its occupants injured. Traffic on this section remained stuck as of 4:00 pm.

An extensive dense cloud of smoke covers part of the Ho Chi Minh City-Long Thanh-Dau Giay Expressway, southern Vietnam April 3, 2018. Photo: Tuoi Tre

A police officer moderates traffic on the Ho Chi Minh City-Long Thanh-Dau Giay Expressway, southern Vietnam April 3, 2018. Photo: Tuoi Tre

An extensive dense cloud of smoke covers part of the Ho Chi Minh City-Long Thanh-Dau Giay Expressway, southern Vietnam April 3, 2018. Photo: Tuoi Tre