Those would be the "oxides" of the elements burned.
oxygen
when a substance is burned it turns into ash.
Oxygen is necessary for a substance to burn. It reacts with the substance in a chemical reaction known as combustion, releasing heat and light energy. Without oxygen, the substance will not be able to sustain a fire.
Oxygen itself does not burn, but it supports combustion. Combustion occurs when a substance reacts with oxygen and releases heat. The temperature at which this reaction occurs varies depending on the substance.
Oxygen is typically needed for a substance to burn. It combines with the fuel to undergo a chemical reaction that produces heat and light.
Oxygen can not burn in air.
Oxygen
Hydrogen and oxygen are already elements. You don't get elements as a product. You get water, which is a compound.
When metals burn in air they form metal oxides.
mageneium oxide
The three elements necessary for combustion to take place are fuel, oxygen, and heat. Fuel provides the substance to burn, oxygen is needed for the reaction to occur, and heat is necessary to initiate the combustion process.
A substance would only burn in a vacuum if it contained an oxidizer. There has to be an oxidizer for there to be fire. That doesn't mean that it requires oxygen, just a substance that facilitates the removal of electrons.