Fires set to spread beyond current boundaries as volunteer fire officer posts emotional letter to Prime Minister

Fire spread maps show the scale of the challenge for firefighters in the day ahead, as a fire officer shares an emotional letter to Scott Morrison. 

An already difficult day for firefighters has ended in tragedy as two RFS volunteers were killed when their truck rolled southwest of Sydney.

Three others are in hospital from the accident and two more firefighters are in a coma after being overcome by flames in a separate incident.

Firefighters are in for a tough day right around the country with Queensland facing terrible conditions and South Australia set to have its worst fire risk day of the summer with catastrophic conditions declared across the state.

Here's how events unfolded on Friday.