The death toll from wildfires on Maui rose to 80 on Friday as search crews scoured the burning ruins of Lahaina and Hawaiian officials tried to determine how the inferno spread so quickly in the historic resort town without warning, Reuters reported.

The fires became the deadliest natural disaster in the state’s history, surpassing a tsunami that killed 61 people on the Big Island of Hawaii in 1960, a year after Hawaii joined the United States.

Authorities have released video from a helicopter that shows the scale of the disaster on Maui:

1,000 homes burned in wildfires on Maui

Officials warned search dog teams could still find more dead in the blaze, which burned 1,000 buildings and left thousands homeless, likely to take years and billions of dollars to rebuild.

“No one has been going into any of these burned structures, and we expect the death toll, unfortunately, to rise significantly here,” U.S. Sen. Brian Schatz of Hawaii told MSNBC.

The Lahaina fire, which spread from vegetation into the city, was still burning but was 85 percent contained, the county said earlier. Two other fires on the island are 80% and 50% contained.

Did the warning sirens go off or not?

Three days after the disaster, it is unclear whether residents received any warning before the fire engulfed their homes.

The island has emergency sirens designed to warn of natural disasters and other threats, but they apparently did not sound during the fire.

“This morning I authorized a comprehensive review to make sure we know exactly what happened and when,” Hawaii Gov. Josh Green told CNN, referring to the warning sirens.

Officials did not provide details on what kind of alerts were sent and whether they were via SMS, email or phone calls.

Green said there were multiple and simultaneous calls, with telecommunications down and firefighters focused on other large fires when Lahaina was most threatened.

In any case, he said, “we will do everything we can to find how best to protect our people in the future.”

“I think it was an impossible situation”

Maui County Fire Chief Bradford Ventura said at a news conference Thursday that the speed of the fire made it “almost impossible” to communicate between first responders and emergency management officials, who normally provide real-time evacuation orders.

“They actually evacuated on their own for quite some time,” he said, referring to residents in the area where the fire first broke out.

County Mayor Richard Bissen told NBC’s “Today” program Friday that he didn’t know if the sirens had gone off, but said the fire was spreading extremely quickly.

“I think it was an impossible situation,” he added.