The death toll in Hawaii's wildfires rose to 99 and could double over the next 10 days, the state's governor said Monday, as emergency personnel painstakingly scoured the incinerated landscape for more human remains.

Last week's inferno on the island of Maui is already the deadliest US wildfire in a century, with only a quarter of the ruins of the devastated town of Lahaina searched for victims so far.

Governor Josh Green said more fatalities are certain, as emergency responders with cadaver dogs work their way through hundreds of homes and burned-out vehicles.

"There are 99 fatalities that are confirmed," he told a press conference Monday.

Speaking to CNN earlier, Green warned that "over the course of the next 10 days, this number could double."

The historic coastal town of Lahaina was almost totally destroyed by the fast-moving blaze last week, with survivors saying there had been no warnings.

The intensity of the fire and scale of the destruction has made identification of human remains difficult, with some corpses disintegrating as they are uncovered by searchers.

Only three of the 99 victims recovered so far could be identified by their fingerprints, said Maui Police Chief John Pelletier.

Police are encouraging those with missing relatives to give DNA samples that might speed up the process.

Around 25 percent of Lahaina had been searched, with that expected to rise to 90 percent by this weekend, said Pelletier.

Jeremy Greenberg, a Federal Emergency Management Agency director, said search conditions were "extraordinarily difficult to work through."

Officials warned of the dangers of unstable buildings and potential airborne toxic chemicals in the area, and said one arrest for trespassing had been made.

Until last week, the town was a bustling tourist hub, packed with shops and restaurants.

Now, "there's nothing to see except full devastation," said Green, who has visited the smoldering streets of rubble and ash multiple times.

Around 1,300 people remain unaccounted for, although delays restoring cell phone communications have made it difficult for residents who fled to reconnect.

"Our hearts will break beyond repair, perhaps, if that means that many more dead. None of us think that, but we are prepared for many tragic stories," Green told CBS.