At least 15 people have been killed in the most severe wildfires to hit southern California for half a century.
The thick choking smoke means residents are forced to stay indoors
Tony Murphy, a British man living in Simi Valley, in Ventura County, one of the worst hit regions, told his story to BBC News Online:
"We have simply been told to stay inside as it is too bad to go outside. Everything is closed, the schools are out and we are just sitting inside the house, waiting.
The sky is black from the smoke and there is ash and debris filling the air, covering absolutely everything. You cannot breathe and your eyes get clogged. It is just not healthy to be outside.
At present we can't see the fire directly, but we know it is moving in a south-westerly direction and we are rather worried as it is encircling us from the north.
We will take our computers and we have two drawers filled with personal documents and our insurance details etc and beyond that we will be piling on top as many clothes as we can so we aren't left with just the clothes on our backs
Simi Valley is about 11 miles (18 kilometres) long and the fires are about five miles away at the Santa Sussana Pass.
Yesterday we went to a DIY store Home Depot and the smoke was so bad that the staff were all wearing masks. There was no power at the store and even the traffic lights were out and the 118 Freeway was closed.
They have already evacuated two tracks of homes in Simi Valley that are closer to the fires and we are watching CBS news for more information.
Dousing the roof
Beyond waiting there is not much we can do. We have hosepipes ready to dampen down the roof of the house.
But one of the problems we've been told of is that some of the houses in the valley have wooden shingle roofs, which are basically made of wooden tiles, and that when the fire comes near sparks of it jump and land on these roofs setting them on fire.
These kinds of roofs are now banned in Simi Valley and no new houses are built with them, but these houses predate the ban.
We have got some things ready in case we have to evacuate. We will take our computers and we have two drawers filled with personal documents and our insurance details etc and beyond that we will be piling on top as many clothes as we can so we aren't left with just the clothes on our backs.
The problem is that there are so few ways out of Simi Valley if we do have to evacuate - I think we'd have to go out through the south.
The glow of the fires can be clearly seen in the sky above Simi Valley
It is very unpleasant at the moment. We have been told to wait inside, if we have air conditioning to turn it on and keep all of the doors and windows closed.
Outside there is dust everywhere - all of the cars are covered in a layer of ash.
The temperature is about 93 degrees (34C) and it has been in the hundreds before that. The valley is flat for about four miles and then its sides rise steeply upwards and basically it is desert. We have had no rain for 90 days and everything is as dry as a tinder box.
In the east you've got Susanna Pass and Rocky Peak, which is on the head of the 118 freeway and the fires are directly above it, then in the west you've got Moor Park, which was badly hit at the weekend.
The sky is black from the clouds but there is an orange glow from the fires themselves. When I was speaking to my daughter on the phone earlier today I opened the window and it just hits you in the back of the throat.
The kids are off because the schools are closed and they are a mixture of nervous and bored, but they simply don't realise how close the fires are - they are just five miles away.
But the TV has been saying that the temperatures are going to drop and that the winds will start coming in from the sea.
Even so, 85,000 acres have already gone."