UPDATE 2.20pm Monday: The NSW Rural Fire Service is warning the fire could spread to new areas such as Kurrajong and Bowen Mountain as weather conditions deteriorate over coming days.
UPDATE 12.05pm Monday: A backburning operation that didn't go to plan destroyed structures in the Mt Wilson and Mt Tomah areas, the ABC has reported
Fire crews lost control of the backburn to the south of the Gospers Mountain fire on Sunday afternoon.
The ABC reported RFS Commissioner Shane Fitzsimmons said the crews in the area were attempting to protect communities around the Bells Line of Road, but "unfortunately things don't always go to plan".
Assessment teams are expected to determine the exact amount of damage done in those areas today.
8am Monday: Properties around Mt Wilson and Mt Tomah are believed to have been destroyed as the Gospers Mountain blaze was upgraded to emergency alert level on Sunday.
An RFS spokesman said there were reports of properties being "impacted" but they were not yet able to confirm specifics. The fire was downgraded to watch and act level overnight.
Blue Mountains mayor Mark Greenhill said the unconfirmed reports of property impacts in the mounts "is the news we did not want to hear".
"Emergency services have been working hard for weeks preparing and those are very prepared communities. However, if property has been impacted we need to be there to support those who have to walk the journey of recovery.
"It is my fear, given the fires around our community, that we have very difficult weeks ahead."
The Terrey Hills RFS Brigade posted a video on Sunday of 70m high flames in Mt Tomah.
The RFS advised people in Mt Tomah, Mt Wilson, Mt Irvine and Bilpin on Monday morning that the fire activity had reduced and there was no immediate threat. Embers may still fall ahead of the main fire front.
The Bells Line of Road is closed at the Mount Tootie Road intersection.
The Blue Mountains Botanic Garden at Mt Tomah posted on its website on Monday: "We are still assessing the extent of the damage, however the impact on some parts of the Garden appears to be significant. Thankfully, most of the Garden's Living Collection along with the main buildings are safe at the moment."
Cr Greenhill said "our exhausted emergency services had a hard day yesterday and many hard days ahead".
"The situation unfolding will be tough and the conditions unprecedented. Now more than ever, we need to find that wonderful community spirit we are known for."
For fire updates visit Fires Near Me.
