Around 10,000 people may have died in just one area of the Philippines hit by Typhoon Haiyan, according to officials.
About 70% - 80% of the area in the path of Haiyan in Leyte province was destroyed, said police chief superintendent Elmer Soria.
"We had a meeting last night with the governor and the other officials. The governor said based on their estimate, 10,000 died," Mr Soria said on Sunday.
The BBC reports that neighbouring Samar island was also badly affected, with reports of 300 people dead and 2000 missing.
The Philippine government has so far only confirmed the deaths of 151 people throughout the country, but hundreds of thousands have been displaced.
One of the worst hit areas is the coastal city of Tacloban where storm surges three to five metres high swept into coastal towns and went deep inland.
"Imagine a strip 1km deep inland from the shore, and all the shanties, everything, destroyed," Interior Secretary Mar Roxas said after landing in Tacloban.
"The devastation is, I don't have the words for it ... It's really horrific. It's a great human tragedy."
The BBC reports the airport there is badly damaged and only military flights are able to operate and there's no clean water, no electricity and very little food.
"The last time I saw something of this scale was in the aftermath of the Indian Ocean tsunami," said Sebastian Rhodes Stampa, the head of a UN disaster assessment coordination team. The 2004 disaster claimed about 220,000 lives.
The ABC reports much of Tacloban is flattened.
Some people survived by clinging to trees. Many others died where they sought shelter, with 20 bodies found in a church near Tacloban.
Looting has been reported in areas where there is no food or water.
And 350,000 people are reported to be displaced from their homes.
Defence Secretary Voltaire Gazmin says there is no power or water and people are desperate.
President Benigno Aquino is to visit the worst areas in the coming days. He fears there will be substantially more casualties.
The ABC reports that the typhoon also hit the city of Iloilo in Central Philippines which has a population of 1.8 million people.
All communications to Iloilo have been cut but a local health administrator told a radio station that 75,000 households have been affected and that the city has been devastated.
He said three hospitals in the city had been damaged and although they had personnel they did not have the resources.
Haiyan was the 24th typhoon to hit the Philippines so far this year.
Last year, Typhoon Bopha flattened three towns in southern Mindanao, killing 1100 people and causing damage of more than $US1 billion.
Vietnam next
Typhoon Haiyan is now heading to Vietnam. The BBC Weather Centre says the typhoon is expected to make landfall late on Sunday local time, although it will have decreased markedly in strength.
Oxfam says about 900,000 people are being evacuated from coastal areas.
The charity's local director, Andy Baker, says the Government is issuing mobile phone alerts to keep people updated about the typhoon's progress.
But he says it's not expected to be as severe as when it hit the Philippines.
The army has been mobilised and about 170,000 soldiers are on stand-by.
