TACLOBAN, Philippines (Reuters) - One of the strongest typhoons ever to make landfall devastated the central Philippines, killing more than 1,000 people in one city alone and 200 in another province, the Red Cross estimated on Saturday, as reports of high casualties began to emerge.

A day after Typhoon Haiyan churned through the Philippine archipelago in a straight line from east to west, rescue teams struggled to reach far-flung regions, hampered by washed out roads, many choked with debris and fallen trees.

The death toll is expected to rise sharply from the fast-moving storm, whose circumference eclipsed the whole country and which late on Saturday was heading for Vietnam.

Among the hardest hit was coastal Tacloban in central Leyte province, where preliminary estimates suggest more than 1,000 people were killed, said Gwendolyn Pang, secretary general of the Philippine Red Cross, as water surges rushed through the city.

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

Witnesses said bodies covered in plastic were lying on the streets. Television footage shows cars piled atop each other.

"The last time I saw something of this scale was in the aftermath of the Indian Ocean Tsunami," said Sebastian Rhodes Stampa, head of the U.N. Disaster Assessment Coordination Team sent to Tacloban, referring to the 2004 earthquake and tsunami.

"This is destruction on a massive scale. There are cars thrown like tumbleweed and the streets are strewn with debris."

The category 5 "super typhoon" weakened to a category 4 on Saturday, though forecasters said it could strengthen again over the South China Sea en route to Vietnam.

Authorities in 15 provinces in Vietnam have started to call back boats and prepare for possible landslides. Nearly 300,000 people were moved to safer areas in two provinces alone - Da Nang and Quang Nam - according to the government's website.

The Philippines has yet to restore communications with officials in Tacloban, a city of about 220,000. A government official estimated at least 100 were killed and more than 100 wounded, but conceded the toll would likely rise sharply.

The national disaster agency has yet to confirm the toll but broken power poles, trees, bent tin roofs and splintered houses littered the streets of the city about 580 km (360 miles) southeast of Manila.

"IT WAS LIKE A TSUNAMI"

The airport was nearly destroyed as raging seawaters swept through the city, shattering the glass of the airport tower, leveling the terminal and overturning nearby vehicles.

"Almost all houses were destroyed, many are totally damaged. Only a few are left standing," said Major Rey Balido, a spokesman for the national disaster agency.

Local television network ABS-CBN showed images of looting in one of the city's biggest malls, with residents carting away everything from appliances to suitcases and grocery items.

Airport manager Efren Nagrama, 47, said water levels rose up to four meters (13 ft) in the airport.

"It was like a tsunami. We escaped through the windows and I held on to a pole for about an hour as rain, seawater and wind swept through the airport. Some of my staff survived by clinging to trees. I prayed hard all throughout until the water subsided."

Across the country, about a million people took shelter in 37 provinces after President Benigno Aquino appealed to those in the typhoon's path to leave vulnerable areas.

"For casualties, we think it will be substantially more," Aquino told reporters.

Officials started evacuating residents from low-lying areas, coastlines and hilly villages as early as three days before the typhoon struck on Friday, officials said. But not all headed the call to evacuate.

"I saw those big waves and immediately told my neighbors to flee," said Floremil Mazo, a villager in southeastern Davao Oriental province.

Meteorologists said the impact may not be as strong as feared because the storm was moving so quickly, reducing the risk of flooding and landslides from torrential rain, the biggest causes of typhoon casualties in the Philippines.

Ferry services and airports in the central Philippines remained closed, hampering aid deliveries to Tacloban, although the military said three C-130 transport planes managed to land at its airport on Saturday.

At least two people were killed on the tourist destination island of Cebu, three in Iloilo province and another three in Coron town in southwestern Palawan province, radio reports said.

"I never thought the winds would be that strong that they could destroy my house," LynLyn Golfan of Cebu said in a television interview while sifting through the debris.

By Saturday afternoon, the typhoon was hovering 765 km west of San Jose in southwestern Occidental Mindoro province, packing winds of a maximum 185 kph, with gusts of up to 220 kph.

The storm lashed the islands of Leyte and Samar with 275-kph wind gusts and 5-6 meter (15-19 ft) waves on Friday before scouring the northern tip of Cebu province. It weakened slightly as it moved west-northwest near the tourist island of Boracay, later hitting Mindoro island.

Haiyan was the second category 5 typhoon to hit the Philippines this year after Typhoon Usagi in September. An average of 20 typhoons strike every year, and Haiyan was the 24th so far this year.

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

(Additional reporting by Rosemarie Francisco, Manuel Mogato and Karen Lema in Manila and Nguyen Phuong Linh in Hanoi; Editing by Jason Szep and Nick Macfie)