As Hawaii residents mourn those killed in ferocious wildfires, officials have warned that the full human and environmental toll is not yet known and the recovery only just beginning.

Twenty dogs and dozens of people are to make their way through neighbourhoods reduced to ash, searching burnt-out cars and homes for the dead.

With the toll currently at 96, it is already the deadliest US wildfire in more than a century.

Two blazes have not yet been completely contained, including the one that demolished the historic town of Lahaina, according to an update from Maui County late on Sunday.

Even where the fire has retreated, authorities have warned that toxic by-products may remain, including in drinking water, after the flames spewed poisonous fumes.

And many people simply have no home to return to – so authorities plan to house them in hotels and holiday rentals.

The blaze that swept into centuries-old Lahaina on Tuesday destroyed nearly every building in the town of 13,000, leaving a grid of grey rubble wedged between the blue ocean and lush green slopes. That fire has been 85% contained, according to the county, while the Upcountry fire has been 60% contained.

Hawaii Fires
Parishioners attend Mass at Sacred Hearts Mission Church in Kapalua, Hawaii (Haven Daley/AP)

“There’s very little left there,” Governor Josh Green said, holding up a map of the area titled “Buildings Damaged in Maui Wildfires Lahaina Area”.

Crews with cadaver dogs have covered just 3% of the search area, Maui Police Chief John Pelletier said on Saturday.

When teams “do come across scenes in houses or businesses, it is very difficult for them because they know, ultimately, they will be sharing with our people that there have been more fatalities. I do expect the numbers to rise”, he said.

The cause of the wildfires is under investigation, and Mr Green said authorities will also examine their response. One fire, for instance, was thought to be out but later flared again.

Hawaii Fires
Volunteers load supplies on to a boat for West Maui (Stephen Lam/San Francisco Chronicle/AP)

In the hours before a wildfire engulfed the town of Lahaina, Maui County officials failed to activate sirens that would have warned the entire population and instead relied on social media posts. Electricity and mobile phone outages further thwarted communication efforts.

Fuelled by a dry summer and strong winds from a passing hurricane, the flames on Maui raced through parched brush – one moving as fast as one mile (1.6km) every minute, according to Mr Green.

“With those kinds of winds and 1,000-degree temperatures, ultimately all the pictures that you will see will be easy to understand,” he said.

Hawaii Fires
Burnt areas in Lahaina on Maui island (Hawaii Department of Land and Natural Resources/AP)

The fires are Hawaii’s deadliest natural disaster in decades, passing a 1960 tsunami that killed 61 people. They also surpassed the 2018 Camp Fire in northern California that left 85 dead and destroyed the town of Paradise.

Maria Lanakila Church in Lahaina was spared the flames that wiped out most of the surrounding community, but with search and recovery efforts ongoing, its members attended Mass up the road on Sunday. The Bishop of Honolulu, the Rev Clarence “Larry” Silva, presided.

During the service, Bishop Silva read a message from Pope Francis, who said he was praying for those who have lost loved ones, homes and livelihoods. He also conveyed prayers for emergency service workers.

Hawaii Fires
About 200 employes from the Westin Maui in Lahaina, Hawaii, are living at the hotel with their families after the wildfires (Rick Bowmer/AP)

Meanwhile, Hawaii officials urged tourists to avoid traveling to Maui as many hotels prepared to house evacuees and first responders.

Mr Green said 500 hotels rooms will be made available for locals who have been displaced, and an additional 500 rooms will be set aside for workers from the Federal Emergency Management Agency.

Some hotels will carry on with normal business to help preserve jobs and sustain the local economy, Mr Green added.

The state wants to work with Airbnb to make sure that rental homes can be made available for locals.