It was touch and go on whether he would have to evacuate, depending on the wind direction.
"When those winds come though they fan those flames so much and they jump big distances. One fire chief yesterday said the fire was moving at the length of a football field per second.
"I would have thought 'the fire's coming I'll pack up the dog and get in the car'. You don't get that chance when it comes at that speed. If those embers blow across the top of you and hit some of the dry bush here, by the time you're about to get out, the fire has completely encircled you and you're gone."
About 15 multi-million dollar mansions have been destroyed in the posh suburb of Bel Air, Williamson said, but no one has died. Officials were able to send texts through cellphone towers that only go to certain areas and first responders had swept through suburbs doing mandatory evacuations.
Officials had closed 265 schools and advised residents to limit outdoor activities, including exercise, as thick plumes of smoke cause intense air pollution.
Bel Air's Skirball fire is about 5 per cent contained. If it continues into the west Hollywood canyons they will turn into a "fire pit" and they would lose million dollar homes "left, right and centre", Williamson said.
"The flames are leaping into the air higher than you'd see coming out of a big gas factory. It's just horrendous.
"It was just scarlet red moon last night. It was like you we're living on another planet. The smoke is so dense."
Winds of 80km/h were expected today as the Santa Ana Wildfire Threat Index coded the forecast as "purple" for the first time - which means "extreme".
Williamson said the fires were exacerbated by a drought that has hung over California for years. This combined with low humidity, high temperatures and strong winds has created the perfect storm for the fires.
"In the canyon, everyone loves the privacy of living among the bush. It's a little bit like living in the Waitakere Ranges. These people love all this privacy but of course they've got this tinder dry bush waiting to explode.
"Everybody is watching it and hopeful that it doesn't come to pass the winds are that strong."