NEW BATAAN, Philippines — A typhoon that killed nearly 600 people and left hundreds missing in the southern Philippines has made a U-turn and is now threatening the country's northwest, officials said Saturday.

The weather bureau raised storm warnings over parts of the main northern island of Luzon after Typhoon Bopha veered northeast. There was a strong possibility the disastrous storm would make a second landfall Sunday, but it might also make a loop and remain in the South China Sea, forecasters said. In either case, it was moving close to shore and disaster officials warned of heavy rains and winds and possible landslides in the mountainous region.

Another calamity in the north would stretch recovery efforts thin. Most government resources, including army and police, are currently focused on the south, where Bopha hit Tuesday.

With many survivors there still in shock, soldiers, police and outside volunteers formed most of the teams searching for bodies or signs of life under tons of fallen trees and boulders swept down from steep hills surrounding the worst-hit town of New Bataan, municipal spokesman Marlon Esperanza said.

"We are having a hard time finding guides," he told The Associated Press. "Entire families were killed and the survivors ... appear dazed. They can't move."

He said the rocks, mud, tree trunks and other rubble that litter the town have destroyed landmarks, making it doubly difficult to search places where houses once stood.

On Friday, bodies found jammed under fallen trees that could not be retrieved were marked with makeshift flags made of torn cloth so they could be easily spotted by properly equipped teams.

Authorities decided to bury unidentified bodies in a common grave after forensic officials process them for future identification by relatives, Esperanza said.

The town's damaged public market has been converted into a temporary funeral parlor. A few residents milled around two dozen white wooden coffins, some containing unidentified remains.

One resident, Jing Maniquiz, 37, said she rushed home from Manila for the wake of two of her sisters, but could not bring herself to visit the place where her home once stood in Andap village. Her parents, a brother and nephew are missing.

"I don't want to see it," she said tearfully. "I can't accept that in just an instant I lost my mother, my father, my brother."

She said that at the height of the typhoon, her mother was able to send her a text message saying trees were falling on their house and its roof had been blown away.

Maniquiz said her family sought refuge at a nearby health center, but that was destroyed and they and dozens of others were swept away by the raging waters.

"We are not hopeful that they are still alive. We just want to find their bodies so that we will have closure," she said.

Mary Joy Adlawan, a 14-year-old high school student from the same village, was waiting for authorities to bury her 7-year-old niece.

Her parents, an elder sister, five nieces and a nephew are missing.

"I don't know what to do," she said as she fixed some flowers on the coffin.

Esperanza said heavy equipment, search dogs and chain saws were brought by volunteers from as far away as the capital, Manila, about 590 miles to the north.

Nearly 400,000 people, mostly from Compostela Valley and nearby Davao Oriental provinces, have lost their homes and are crowded inside evacuation centers or staying with relatives.

The typhoon plowed through the main southern island of Mindanao, crossed the central Philippines and lingered over the South China Sea for the past two days. It made a U-turn Saturday and is now threatening the northwestern Ilocos region.

President Benigno Aquino III, after visiting the disaster zone, declared a state of national calamity late Friday to speed up rescue and rehabilitation, control prices of basic commodities in typhoon-affected areas and allow the quick release of emergency funds.

In Bangkok, Thailand, U.N. humanitarian chief Valerie Amos said the Philippines had appealed for international aid. She said many countries have already provided assistance, but did not specify the amounts.

Officials say 276 people were killed in Compostela Valley, including 155 in New Bataan, and 277 in Davao Oriental. About 40 people died elsewhere and nearly 600 are still missing, 411 from New Bataan alone.

Davao Oriental Gov. Corazon Malanyaon told the AP that clean water and shelter were the biggest problem in three towns facing the Pacific Ocean. She said she imposed a curfew there and ordered police to guard stores and shops to stop looting.

The Philippines is also counting economic losses. Banana growers reported that 34,600 acres of export banana plantations, equal to 18 percent of the total in Mindanao, were destroyed. The Philippines is the world's third-largest banana producer and exporter, supplying international brands such as Dole, Chiquita and Del Monte.

Stephen Antig, executive director of the Pilipino Banana Growers and Exporters Association, said losses were estimated at 12 billion pesos ($300 million), including 8 billion pesos ($200 million) in damaged fruits that had been ready for harvest, and the rest for the cost of rehabilitating farms, which will take about a year.

At the Vatican, Pope Benedict XVI expressed closeness to the people hit by the typhoon. "I pray for the victims, for their families and for the many homeless," the pontiff said Saturday, addressing pilgrims and tourists from his studio window overlooking St. Peter's Square.