The death toll, largely from the city of Palu, is expected to keep rising as areas cut off by the damage are reached. The magnitude 7.5 earthquake struck at dusk Friday and generated a tsunami said to have been as high as 6 meters (20 feet) in places.

Local Army Commander Tiopan Aritonang said 545 bodies for the grave would be brought from one hospital alone. The trench dug in Palu was 10 meters by 100 meters (33 feet by 330 feet) and can be enlarged if needed, said Willem Rampangilei, chief of Indonesia’s National Disaster Mitigation Agency.

“This must be done as soon as possible for health and religious reasons,” he said. Indonesia is majority Muslim, and religious custom calls for burials soon after death, typically within one day.

Local military spokesman Mohammad Thorir said the area adjacent to a public cemetery can hold 1,000 bodies. All of the victims, coming from local hospitals, have been photographed to help families locate where their relatives were buried. Video footage showed residents walking from body bag to body bag, opening the tops to check to see if they could identify faces.

Around midday, teams of workers, their mouths covered by masks, carried 18 bodies and laid them in the trench. A backhoe waited to push soil on top of the dead. More burials were expected to follow.

Military and commercial aircraft were delivering some aid and supplies. But there was a desperate need for heavy equipment to reach possible survivors buried in collapsed buildings, including an eight-story hotel in Palu where voices were heard in the rubble.

People suffering from a lack of food and supplies were also becoming more desperate. Local television said around 3,000 residents had flocked to the Palu airport trying to get out. Footage showed some people screaming in anger because they were not able to board departing military aircraft.

“We have not eaten for three days!” one woman yelled. “We just want to be safe!”

Indonesian President Joko “Jokowi” Widodo authorized for the country to accept international help for the disaster, Thomas Lembong, chair of Indonesia’s Investment Coordinating Board, tweeted Monday morning. It wasn’t immediately clear what type of help was being authorized, but the stricken areas needed medical supplies, food and water.

“We will send food today, as much as possible with several aircraft,” he told journalists in the capital, Jakarta, adding a supply of fuel was also set to arrive.

A 25-year-old woman was found alive Sunday evening in the ruins of the Roa-Roa Hotel, according to the National Search and Rescue Agency, which released photos of the her lying on a stretcher covered in a blanket. A number of other survivors were still being found and a few were being pulled from buildings in different locations.

The confirmed toll of 844 released by disaster agency spokesman Sutopo Purwo Nugroho on Monday afternoon was an increase of only 12 since the previous day, with nearly all of those from Palu. The regencies of Donggala, Sigi and Parigi Moutong — with a combined population of 1.2 million — had yet to be fully assessed. Nearly 50,000 people have been displaced from their homes, he said.

It was the latest natural disaster to hit Indonesia, which is frequently struck by earthquakes, volcanic eruptions and tsunamis because of its location on the “Ring of Fire,” an arc of volcanoes and fault lines in the Pacific Basin. In December 2004, a massive magnitude 9.1 earthquake off Sumatra island in western Indonesia triggered a tsunami that killed 230,000 people in a dozen countries. More recently, a powerful quake on the island of Lombok killed 505 people in August.

In Donggala, the site closest to the earthquake’s epicenter, aerial footage on Metro TV showed the sugary blond sands of beaches swept out to sea, along with some buildings. Some buildings in the town were severely damaged, with plywood walls shredded and chunks of concrete scattered on the pavement. Much of the damage, however, appeared limited to the waterfront.

Palu, which has more than 380,000 people, was strewn with debris from the earthquake and tsunami. A heavily damaged mosque was half submerged and a shopping mall was reduced to a crumpled hulk. A large bridge with yellow arches had collapsed.

The city is built around a narrow bay that apparently magnified the force of the tsunami as the waves raced into the tight inlet. Nugroho, the disaster agency spokesman, said waves were reported as high as 6 meters (20 feet) in some places.

In one devastated area in Palu, residents said dozens of people could still be buried in their homes.

“The ground rose up like a spine and suddenly fell. Many people were trapped and buried under collapsed houses. I could do nothing to help,” resident Nur Indah said, crying. “In the evening, some of them turned on their cellphones just to give a sign that they were there. But the lights were off later and the next day.”

With hundreds injured, earthquake-damaged hospitals were overwhelmed.

Indonesia is a vast archipelago of more than 17,000 islands home to 260 million people. Roads and infrastructure are poor in many areas, making access difficult in the best of conditions.

The disaster agency has said that essential aircraft can land at Palu’s airport, though AirNav, which oversees aircraft navigation, said the runway was cracked and the control tower damaged.

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Associated Press writers Margie Mason in Jakarta, Indonesia, and Stephen Wright in Makassar, Indonesia, contributed to this report.