"People are walking like zombies looking for food," said Jenny Chu, a medical student in Leyte. "It's like a movie."
Most of the deaths appear to have been caused by surging sea water strewn with debris that many said resembled a tsunami, leveling houses and drowning hundreds of people in one of the worst disasters to hit the typhoon-prone Southeast Asian nation.
The national government and disaster agency have not confirmed the latest estimate of deaths, a sharp increase from initial estimates on Saturday of at least 1,200 killed by a storm whose sustained winds reached 313 km per hour with gusts of up to 235 mph.
"We had a meeting last night with the governor and the other officials. The governor said, based on their estimate, 10,000 died," Soria told Reuters. "The devastation is so big."
About 300 people died in neighboring Samar province, where Haiyan first hit land on Friday as a category 5 typhoon, with 2,000 missing, said a provincial disaster agency official.
Nearly 480,000 people were displaced and 4.5 million "affected" by the typhoon in 36 provinces, the national disaster agency said, as relief agencies called for food, water, medicines and tarpaulins for the homeless.
International aid agencies said relief efforts in the Philippines were stretched thin after a 7.2 magnitude quake in central Bohol province last month and displacement caused by a conflict with Muslim rebels in southern Zamboanga province.
Witnesses and officials described chaotic scenes in Leyte's capital, Tacloban, a coastal city of 220,000 about 360 miles southeast of Manila which bore the brunt, with hundreds of bodies piled along roads and pinned under wrecked houses.
The city lies in a cove where the seawater narrows, making it susceptible to storm surges.
The city and nearby villages as far as one kilometer (just over half a mile) from shore were flooded, leaving floating bodies and roads choked with debris from fallen trees, tangled power lines and flattened homes.
Many Internet users urged prayers and called for aid for survivors in the largely Roman Catholic nation on social media sites such as Twitter.
Looters rampaged through several stores in Tacloban, witnesses said, taking whatever they could find as rescuers' efforts to deliver food and water were hampered by severed roads and communications. A TV station said ATM machines were broken open.
Mobs attacked trucks loaded with food, tents and water on Tanauan bridge in Leyte, said Philippine Red Cross chairman Richard Gordon. "These are mobsters operating out of there."
President Benigno Aquino said the government had deployed 300 soldiers and police to restore order and that he was considering introducing martial law or a state of emergency in Tacloban to ensure security.