AT least 63 people have died in a Northern California wildfire while 631 people are sill unaccounted for, authorities have said.

Butte County Sheriff Kory Honea revealed the increased missing persons total at a news conference on Thursday, having put the figure at 130 just a day earlier.

Honea said the original total was a partial count, and that after authorities went back through all emergency calls and other reports of missing people from the past week, they came up with the new number. The list probably included some who had fled the blaze and did not realise they had been reported missing, he added.

“The chaos that we were dealing with was extraordinary,” he said of the early crisis hours last week. “Now we’re trying to go back out and make sure that we’re accounting for everyone.”

Authorities also reported seven more fatalities, bringing the total to 63, in the deadliest wildfire in state history.

Ten years ago, as two wildfires advanced on the town of Paradise, residents jumped into their vehicles to flee and got stuck in gridlock. That led authorities to devise a staggered evacuation plan – one that they used when fire came again last week.

But some survivors said that by the time they got warnings, the flames were already extremely close, and they barely escaped with their lives. Others said they received no warnings at all.