山火 vs 野火 vs 丛林大火: Chinese for "bushfire"
These words are all straight-forward in Chinese:


山火 = mountain fire
野火 = fire in the fields
丛林大火 = jungle fire
Forest fire = 森林大火, or 林火
Forest fire on a mountain (explicit) = 山林大火


Note 丛林 means jungle/bush; Forest in general is translated into 森林; 野 in 野火 means 田野(field) rather than 狂野(out of control), but even many native speakers misunderstood.

So to answer your question,


山火 is not a generic word for out-of-control fire. It means mountain fire.
野火 means fire in the fields. It sounds a little less formal than the other words but still fine to use. News broadcaster may choose long form 田野大火 or 山野大火。
丛林大火 means jungle fire.
When you want to say 'fires in a forest on a mountain', any of the following is fine: 山火，林火，森林大火，山林大火。