Authorities say more than 600 people are missing in the wake of the Northern California wildfire known as the Camp Fire, a number that has ballooned rapidly and is expected to continue to fluctuate. The Butte County Sheriff's Office had said late Wednesday that 130 people were missing; on Thursday evening, the list had grown to 631.

However, that number may include people who escaped to safety and do not realize they are being searched for.

The death toll also rose after seven sets of remains were discovered on Thursday. At least 63 people have died in the fire, which has burned through at least 218 square miles of land and consumed the town of Paradise.

The fire is the deadliest, and the most destructive, in California history. Nearly 10,000 homes have been destroyed.

No official cause for the fire has been identified; the blaze is currently 40 percent contained.

Butte County Sheriff Kory Honea told reporters at a news conference Thursday evening that the list of missing people ballooned as a result of staff going back through calls that came in during the beginning of the fire emergency. Honea said that when the blaze erupted one week ago, "the chaos we were dealing with was extraordinary."

He added that the number of unaccounted-for people is likely to keep shifting as existing cases are resolved and new calls come in from people looking for friends and relatives.

Many of the missing are elderly, according to lists released by county officials. A number of them are in their late 80s and 90s.

Reuters notes that Paradise had long been described by realtors as a perfect place for retirement. The wire service reports:

"Relatives of retired U.S. Navy veteran David Marbury, 66, are waiting to hear from him. No one has managed to speak with him since the wildfire began, and relatives' phone calls have gone directly to his voicemail."On Thursday, Marbury's landlord confirmed to relatives that his duplex in Paradise had burned down. Sheriff?s officials told them his car was still in the garage." 'I really hope he's still alive and we're going to be able to see him,' Marbury's niece Sadia Quint, 30, told Reuters by phone. ' We just hope that he's still with us.' "

In a strange tangent to the ongoing search for victims of the fire, officials announced that law enforcement officers on Thursday had shot and killed a fugitive in a staging area used for fire operations.

Butte County District Attorney Michael Ramsey told reporters at the news conference that the man had been sought by authorities since July. The man was pointed out by a civilian, Ramsey said; officers confronted him, followed him in a high-speed car chase, and then stopped him by using spike strips that flattened the tires on his sedan.

The man removed his hand from his right pocket and pointed a metallic object at the officers, Ramsey said. Six officers opened fire, and the man was pronounced dead at the scene. A police dog was killed by friendly fire, and a dog that the man had in his car, which had attacked the police dog, was shot and killed, as well.

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