The death toll from a super typhoon that swept away towns in the Philippines could to more than 10,000, authorities have warned, making it the country's worst recorded natural disaster.

The estimates on Sunday came as rescue workers appeared overwhelmed in their efforts to help survivors of Typhoon Haiyan, which inundated and battered large parts of the archipelago on Friday.

The regional police chief for eastern Leyte province said 10,000 people were believed to have died on that island alone, mostly by drowning and from collapsed buildings.

"We had a meeting last night with the governor and, based on the government's estimates, initially there are 10,000 casualties [dead]," Chief Superintendent Elmer Soria told reporters in the provincial capital, Tacloban.

Soria said that as much as 80 percent of the area in the path of Haiyan in Leyte province was destroyed.

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Al Jazeera's Wayne Hay, reporting from Tacloban, said the city was in absolute disarray.

"People are still searching for missing friends and family members," he said, "and for any food and water they can get their hands on".

He reported that the military was arriving at the destroyed Tacloban airport and bringing some supplies, but that it was "clearly still not enough".

"One of the biggest problems is shelter, and those military planes have been taking a very small number of people away to other parts of the country," but most people have been staying in makeshift shelters in overcrowded Tacloban schools and sports stadiums, he said.

'Imagine everything destroyed'

President Benigno Aquino III landed in Tacloban on Sunday to get a first-hand look at the devastation.

Aquino said the casualties will be "substantially more" than the official count of 151 - but gave no figure or estimate.

"Imagine a strip one kilometre deep inland from the shore, and all the shanties, everything, destroyed," Interior Secretary Mar Roxas said after visiting coastal towns in Leyte.

Earlier, the Philippines Red Cross estimated that more than 1,000 people had been killed in Tacloban and at least 200 in hard-hit Samar province when one of the strongest typhoons in history slammed into the country.

Gwendolyn Pang, secretary-general of the Philippine Red Cross, said on Saturday that those numbers came from preliminary reports by Red Cross teams in Tacloban and Samar, among the most devastated areas hit by Typhoon Haiyan on Friday.

"An estimated more than 1,000 bodies were seen floating in Tacloban as reported by our Red Cross teams," she told Reuters. "In Samar, about 200 deaths. Validation is ongoing."

She said she expected a more exact number to emerge after a more precise counting of bodies on the ground in those regions.

Communications cut off

The Philippines has yet to resume communications with officials in Tacloban, a city of about 220,000 that suffered the worst of the typhoon. Reports say the sea flooded the entire city.

It was a similar situation in the town of Palo, further south. It was said to be under three and a half metres of water.

One UN official said the damage was similar to the devastation caused by the Indian Ocean tsunami in 2004.

The 'category five' storm weakened after hitting six spots in the Philippines and has been downgraded to 'category four', though forecasters said it could strengthen again over the South China Sea on its course to hit Vietnam.

More than 883,000 people have been evacuated in central and northern Vietnam as forecasters predict the typhoon will make landfall there on Monday morning.

According to Vietnam's national Television station, VTV, Six people were killed and dozens wounded during heavy winds and storms in central provinces as Haiyan approached the coast, even though it had weakened substantially since hitting the Philippines.

Despite weakening, the storm is likely to cause heavy rains, flooding, strong winds and mudslides as it makes its way north in the South China Sea.

An average of 20 typhoons strike the Philippines every year, and Haiyan was the 24th in 2013. 

Last year, Typhoon Bopha flattened three towns in southern Mindanao, killing 1,100 people and causing damage of more than $1bn.

Source: Al Jazeera and agencies