People can go into shock and die.

"Shock may result from trauma, heatstroke, blood loss or an allergic reaction. It also may result from severe infection, poisoning, severe burns or other causes. When a person is in shock, their organs don't get enough blood or oxygen. If shock is not treated, it can lead to permanent organ damage or even death."

https://www.mayoclinic.org/first-aid/first-aid-shock/basics/....