Boleskine House, on the banks of Loch Ness near Foyers in the Highlands, is still ablaze and fire crews have been unable to get inside the building to check for casualties.
About 60 per cent of the building had been destroyed by the time fire crews arrived shortly after 1:40pm on Wednesday.
Two appliances were initially sent to the scene, one from Foyers and another from Inverness.
Further pumps were later sent from Inverness and Beauly, along with a water carrier from Inverness, a pump from Dingwall and an incident support unit from Inverness.
Crews continued their efforts on the west wing of the building while firefighters in breathing apparatus are using four main jets to tackle the blaze.
Crowley, who died in 1947 aged 73, was an occultist, mystic and magician known as “the Great Beast” and ‘’the wickedest man in the world’’.
He was a sexually liberated recreational drug-taker long before the 1960s social revolution and followed a ‘’Do what thou wilt’’ philosophy.
Interest in his teachings grew in the 1960s and rock stars such as Jimmy Page were influenced by his ideas.
Page bought the house at the height of Led Zeppelin’s fame in 1970 as a restoration project and a base for songwriting, but spent little time there and eventually sold it in 1992.
It has since been used as a private residence and a guest house, and was put up for sale in 2009 for £176,000.