What is the first action to take when treating a serious burn?

Cooling the burn under running water for at least 10 minutes is critical because it helps to reduce the temperature of the affected area, alleviating pain and minimizing further tissue damage. This action also helps to prevent the burn from progressing into deeper tissue layers. Cooling the burn effectively halts the burning process by washing away any residual heat and can also reduce swelling.

In the context of burn treatment, it's important to avoid applying ice directly to the burn, as this can cause further damage to the skin and tissue. Covering the burn with a cloth too soon can trap heat, and immediately wrapping it with a bandage may hinder the cooling process and lead to complications. Therefore, the initial step should focus on cooling the burn properly to ensure optimal care.