News 12/AP - An estimated 1,200 people have been killed by the massive typhoon that made landfall in the Philippines yesterday, a Red Cross official has told CNN.

"We estimate 1,000 people were killed in Tacloban and 200 in Samar province," Gwendolyn Pang, secretary general of the Philippine Red Cross, said of two coastal areas where Haiyan hit first as it began its march Friday across the archipelago.

Pang, however, emphasized that it was "just an estimate." The Red Cross said it would have more precise numbers Sunday. But experts predicted that it will take days to get the full scope of the damage wrought by a typhoon described as one of the strongest to make landfall in recorded history.

On Saturday, more than 330,000 people were still in 1,223 evacuation centers, and the government had accepted a U.N. offer of international aid.

The Philippine interior secretary says officials expect "a very high number of fatalities" from one of the strongest typhoons on record. He describes the damage in the city of Tacloban as "really horrific."

The storm, named Typhoon Haiyan, slammed into six central Philippine islands on Friday, wiping away buildings and leveling seaside homes. More than 100 deaths were on the hardest-hit Leyte Island, where Tacloban is located, said national disaster agency spokesman Maj. Reynaldo Balido.

Civil aviation authorities in Tacloban, about 360 miles southeast of Manila, reported that the seaside airport terminal was "ruined." U.S. Marine Col. Mike Wylie says military planes could still land with relief aid.

But after arriving in Tacloban on Saturday, Interior Secretary Max Roxas said it was too early to know how many people had died in the storm, which was heading toward Vietnam after moving away from the Philippines.

"The rescue operation is ongoing, we expect a very high number of fatalities as well as injured," he said. "All systems, all vestiges of modern living - communications, power, water - all are down. Media is down, so there is no way to communicate with the people in a mass sort of way."

The Philippine Red Cross and its partners were preparing for a major relief effort "because of the magnitude of the disaster," said the agency's chairman, Richard Gordon.

U.S. Marine Col. Mike Wylie surveyed the damage in Tacloban prior to possible American assistance. "The storm surge came in fairly high and there is significant structural damage and trees blown over," said Wylie, who is a member of the U.S.-Philippines Military Assistance Group based in Manila.

U.S. Secretary of State John Kerry said in a statement that America "stands ready to help."

"The water was as high as a coconut tree," said 44-year-old Sandy Torotoro, a bicycle taxi driver who lives near the airport with his wife and 8-year-old daughter. "I got out of the jeep and I was swept away by the rampaging water with logs, trees and our house, which was ripped off from its mooring."

ABS-CBN television anchor Ted Failon, who was able to report only briefly Friday from Tacloban, said the storm surge was "like the tsunami in Japan."

"The sea engulfed Tacloban," he said, explaining that a major part of the city is surrounded on three sides by the waters between Leyte and Samar islands.

Ferocious winds felled large branches and snapped coconut trees. A man was shown carrying the body of his 6-year-old daughter who drowned, and another image showed vehicles piled up in debris.

Nearly 800,000 people were forced to flee their homes and damage was believed to be extensive. About 4 million people were affected by the typhoon.

Relief workers said they were struggling to find ways to deliver food and other supplies, with roads blocked by landslides and fallen trees.

The storm's sustained winds weakened Saturday to 163 kph (101 mph) with stronger gusts as it blew farther away from the Philippines toward Vietnam.

Vietnamese authorities in four central provinces began evacuating more than 500,000 people from high risk areas to government buildings, schools and other concrete homes able to withstand strong winds.

AP Wire services contributed to this report.