The number of missing after a California mudslide has fluctuated wildly, due to shifting definitions, the inherent uncertainty that follows a natural disaster, and just plain human error.

As of early Friday, the number was down to five, but Santa Barbara County spokeswoman Amber Anderson said it could continue to fluctuate.

Early Thursday, the number provided by authorities went from 48, down to eight. Officials said a clerical mistake led to the figure of 48 being released.

At a news conference later Thursday, Santa Barbara County Sheriff Bill Brown said the number was 43, an "inclusive" figure that encompassed several definitions of "missing."

"I know it sounds like it's a constantly moving number," Brown said. "There hasn't been a sound definition of what constitutes a missing person."

It could include everything from urgent, active missing-persons cases being worked by detectives to calls received from acquaintances saying they hadn't been able to reach someone they believe was in Montecito on Tuesday morning when mudslides swept through town and killed 17 people.

Authorities would not specify how many people were in each category.

Brown said some of those on the missing list may simply have left the area before or after the mudslides or may just be out of touch with the family and friends looking for them.

Similar issues emerged in last year's wine country wildfires in Northern California, where at times thousands were reported missing, the overwhelming majority simply people whose communication with friends and family had been cut off by the fires.

Brown did say that of the 17 people he announced were missing Wednesday, some were identified as among the dead and were crossed off the list.

He did not believe, he said Thursday, that there were 43 more dead to be discovered, or even a figure close to that.