National Guard troops have joined the grim search for more victims in the ruins of an incinerated northern California town, while the death toll climbed to 63 in the most deadly and destructive wildfire in the state’s history.

The latest fatality count was announced on Friday (Thursday local time) as authorities released a revised list of more than 600 people reported missing by loved ones after flames largely obliterated the Sierra foothills town of Paradise, about 280 km north of San Francisco, last Thursday.

The majority on the list were over the age of 65, and the revised official roster has 631 people missing. Nearly 230 people were initially reported as missing in the killer blaze, dubbed the Camp Fire.

Most of those who remain unaccounted for are from Paradise, once home to 27,000 people.

Nearly 9000 homes and other buildings burned to the ground in and around Paradise, and an estimated 50,000 people remained under evacuation orders in the area.

Adding to the misery of some survivors was an outbreak of norovirus, a highly contagious gastrointestinal illness, at a shelter housing about 200 evacuees in the nearby city of Chico.

Public health agency spokeswoman Lisa Almaguer said at least 20 people may have caught the virus.

The footprint of the eight-day-old fire grew to 57,000 hectares as of Thursday, even as diminished winds and rising humidity helped firefighters shore up containment lines around more than a third of the perimeter.

Still, the ghostly expanse of empty lots covered in ash and strewn with twisted wreckage and debris made a strong impression on Governor Jerry Brown, US Interior Secretary Ryan Zinke and other officials who toured the devastation on Wednesday.

“This is one of the worst disasters I’ve seen in my career, hands down,” Brock Long, head of the Federal Emergency Management Agency, told reporters in Chico.

“It looks like a war zone. It is a war zone,” Brown said.

In Butte County, the search for more human remains kicked into high gear as a National Guard contingent of 50 military police officers joined dozens of search-and-recovery workers and at least 22 cadaver dogs, Sheriff Kory Honea said.

The remains of eight more fire victims were found on Wednesday, raising the official number of fatalities to 63 – far exceeding the previous record from a single wildfire in California history when 29 people were killed in Los Angeles in 1933.

Sheriff Honea invited relatives of the missing to provide DNA samples to compare against samples taken from newly recovered remains in hopes of speeding up identification of the dead.

But he acknowledged it was possible some of the missing might never be found.