What was the cause of death of 39 victims in the "truck death case"?

According to "Overseas Network" reported on February 12, the autopsies of the remains of 39 Vietnamese victims in the British death van case have ended, and the British police announced the preliminary investigation results: 39 victims died of suffocation, hypoxia and high fever. The police recently arrested two more suspects.

According to the report, among the 39 victims, including 3 1 man and 8 women, their cause of death was "suffocation due to lack of oxygen in confined space and hyperthermia".