What is polytrauma, that caused One Direction singer Liam Payne's death?

An autopsy revealed One Direction singer Liam Payne died from "polytrauma" and "an internal and external haemorrhage". Polytrauma occurs during high-impact events such as car accidents or falls, but can also arise during incidents of violence, natural disasters or combat. Polytrauma, in medical terms, causes complex and potentially fatal complications since it affects multiple systems in the body.