Palu, Indonesia (CNN) Mass graves were dug Monday as Indonesian authorities rushed to bury hundreds of people killed by an earthquake and tsunami that cracked streets, tore down buildings and washed away homes on the island of Sulawesi.

Three days after the disaster, the streets of the provincial capital Palu were still covered in debris and bodies thrown about by a magnitude 7.5 earthquake that triggered tsunami waves up to three-meters-high (10 feet).

Authorities raised the toll again Monday to 844 dead, and warned that more bodies were likely to be found as heavy equipment moved in to clear the rubble.

Conditions in the devastated area are grim, with food and water supplies running low and few buildings sturdy enough to offer safety from any aftershocks.

Body bags lie in an open ditch in Palu, Indonesia.

As they waited for aid Sunday, survivors took matters into their own hands, entering shops and wheeling away trolleys filled with food and water. At a gas station Monday, a CNN crew saw people opening up a tank from under the ground and using ladles to scoop up fuel.

Hundreds rushed to the airport hoping to catch one of the few flights out of the area. One man told CNN Monday he had been waiting there two days. A woman said she feared for her and her baby's safety due as residents raided shops for food and water.

In total, an estimated 2.4 million people were affected by the disaster, Indonesian Disaster Management Agency spokesman Sutopo Purwo Nugroho said. Some 600 people were hospitalized and more than 48,000 have been displaced.

Photos: In pictures: Earthquake and tsunami strike Indonesia Soldiers carry a dead body from the ruins of houses in Palu, Indonesia, on Thursday, October 4. Hide Caption 1 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia An injured person rests inside a Palu hospital on October 4. Hide Caption 2 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Indonesian soldiers in Makassar prepare to welcome a military ship with evacuees on October 4. Hide Caption 3 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Furniture sits partially submerged in mud in a Palu house on October 4. Hide Caption 4 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia This aerial image shows local residents lining up for gasoline in Palu on October 4. Hide Caption 5 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A damaged building in Palu on Wednesday, October 3. Hide Caption 6 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A victim's face is bandaged at a makeshift hospital in Palu on October 3. Hide Caption 7 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Quake survivors salvage items from the debris of a factory complex in Palu. Hide Caption 8 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A woman mourns in Palu on Tuesday, October 2, after her relatives were found to have died in the earthquake. Hide Caption 9 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia People ride a scooter past a partially submerged mosque in Palu on October 2. The mosque was knocked from its foundation during the quake and tsunami. Hide Caption 10 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A man stands atop a car and other debris in Palu. Hide Caption 11 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A ship that was swept ashore during the tsunami rests near houses in Donggala on October 2. Hide Caption 12 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Indonesian soldiers bury earthquake victims in a mass grave in Poboya on October 2. Hide Caption 13 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A woman makes her way through rubble in the Palu neighborhood of Balaroa on October 2. Hide Caption 14 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia People survey the wreckage of a bridge near Talise Beach in Palu. Hide Caption 15 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Survivors scuffle for live chickens being distributed from a police truck in Palu on October 2. Hide Caption 16 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A boy stands in front of a stranded ship in Donggala on October 2. Hide Caption 17 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A family on a motorcycle waits to learn the status of relatives on October 2. Hide Caption 18 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia An aerial view of a devastated area in Palu on Monday, October 1. Hide Caption 19 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A ship is stranded on the shore in Wani on October 1. Hide Caption 20 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Bodies are carried to a mass grave in Palu's Balaroa village on October 1. Hide Caption 21 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A man takes a photo on a damaged bridge in Palu on October 1. Hide Caption 22 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia People ride past a boat and other debris in Palu on October 1. Hide Caption 23 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A young girl cries outside the Palu airport after it reopened on October 1. Hundreds rushed to the airport hoping to catch one of the few flights out of the area. Hide Caption 24 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia The ruins of a collapsed mosque are seen in Palu on October 1. Hide Caption 25 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia An Indonesian soldier stands guard at a service station as people line up to fill gasoline containers on October 1. Hide Caption 26 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Another scene of devastation in Palu. Homes, business and vehicles along the coast were washed away by violent tsunami waves. Roads and bridges were destroyed. Hide Caption 27 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Survivors rest outside the airport as they wait for a flight out of Palu on October 1. Hide Caption 28 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia People wait in line for fuel in Palu. Hide Caption 29 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Rescuers try to free a 15-year-old earthquake survivor who was trapped in the flooded ruins of a collapsed house in Palu on Sunday, September 30. Hide Caption 30 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia The remains of a Palu building after it collapsed following the earthquake. Hide Caption 31 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Rescuers move a survivor from a collapsed restaurant building in Palu. Hide Caption 32 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia A man searches for his belongings in the ruins of his house in Palu on Saturday, September 29. Hide Caption 33 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Palu residents gather to look at a collapsed building in the aftermath of the quake and tsunami. Hide Caption 34 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Indonesian soldiers load emergency supplies onto a military plane at a base in Jakarta, Indonesia's capital, before heading to Palu on September 29. Hide Caption 35 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia People carry a victim in Palu on September 29. Hide Caption 36 of 37 Photos: In pictures: Earthquake and tsunami strike Indonesia Palu residents make their way along a street full of debris on September 29. Palu is a coastal city of about 350,000. Hide Caption 37 of 37

In the chaos after the quake, more than 1,000 inmates from five prisons had fled, according to CNN Indonesia. Authorities have urged them to return within one week.

Weekend's horrors

The earthquakes were just the start of the horror for residents of Palu and surrounding areas. The largest tremor triggered a tsunami that sent waves of "about three meters high" to the beaches of Palu and Donggala.

Homes, business and vehicles along the coast were washed away by the violent waves. Roads and bridges were destroyed.

Mia, 40, was at the Ramayana shopping mall in Palu with her daughters when the ground started shaking.

"I just finished my shopping and went to the cashier, suddenly everything got dark and the walls started falling around us, it was horrible," said Mia, who like many Indonesians only goes by one name. She said she ran down a broken escalator with her daughters. They made it out alive, but not all were so lucky.

Across the region, first responders are continuing to dig through the rubble, sometimes by hand, in the hopes of finding survivors who were trapped by the massive quake or the destructive tsunami that followed.

In the residential area of Patobo, there are fears that many could have been killed when 744 homes were buried in mud, Nugroho said Monday.

In Palu, workers scrambled to rescue about 50 people trapped beneath the debris of the Roa Roa hotel.

This aerial picture shows the remains of the Roa Roa hotel.

Aerial images showed the eight-floor building completely collapsed, and video posted by Nugroho to Twitter showed orange-clad responders carrying an individual on a stretcher through the rubble.

Evakuasi korban tertimbun gempa di Hotel Roa-Roa Kota Pqluterus dilakukan Tim SAR Gabungan dikoordinir Basarnas. Diperkiran terdapat 50 orang di bawah reruntuhan bangunan. Alat berat diperlukan untuk evakuasi. pic.twitter.com/LGWwp3OEhE — Sutopo Purwo Nugroho (@Sutopo_PN) September 30, 2018

One of the guests at the hotel was a 39-year-old South Korean national, according to the South Korean embassy in Indonesia. The man had been in the region for a paragliding competition.

Only two foreigners, a Malaysian and the South Korean national, are still unaccounted for, Nugroho said. Three French nationals previously missing have been found. The Indonesian government has evacuated 114 foreign nationals.

As of Sunday, there were no reports of US citizens affected by the quake, the US Embassy in Jakarta told CNN.

Aid efforts

Disaster officials say the inability to access the worst-affected areas has hampered their efforts, as they were unable to quickly deliver aid and heavy machinery used to rescue survivors. The Mutiara Sis Al Jufri Airport in Palu was closed for 24 hours after the tsunami but has since reopened to limited flights.

Aid has trickled into the city of Palu, but first responders have only recently reached the Donggala regency, home to more than 300,000 people. They were closest to the epicenter of the largest, magnitude 7.5 earthquake that struck Friday, before the tsunami washed into the long, narrow bay, past the town of Donggala and into Palu.

"The Indonesian Red Cross is racing to help survivors, but we don't know what they'll find there," said Jan Gelfand, who heads the International Red Cross delegation in Indonesia Sunday. "I don't think we've quite seen the worst of things yet."

Priority will be given to evacuating survivors and allowing aid workers to bring in food and fresh water, said Indonesian President Joko Widodo, who visited the disaster site on Sunday.

Widodo has authorized the country to request international aid relief.

The European Union and South Korea have offered $1.7 million and $1 million respectively, while the Australian government has said it's working with Indonesia to identify options for assistance.

'Are you ready?'

Bambang Soesatyo, speaker of the People's Representative Council and a member of Golkar Party, told reporters Sunday the government needs to increase the scale of relief operations in the affected area.

Many people had to sleep on the side of the road and patients were treated in open spaces. Residents are still worried about aftershocks and are afraid to return home, said Soesatyo.

Hundreds of families are already mourning the loss of their loved ones, including an air traffic controller who's been hailed as a hero.

Anthonius Gunawan Agung, 21, died in the hospital after he jumped off the traffic control tower at the Palu airport when he thought the tower was collapsing.

Telah wafat saat menjalankan tugasnya sebagai personel layanan navigasi penerbangan, Saudara Anthonius Gunawan Agung, Air Traffic Controller (ATC) AirNav Indonesia Cabang Palu pada Sabtu (29/09).#RIPAgung #DoaUntukSulteng#PrayforDonggala #PrayforPalu pic.twitter.com/6Wpobp3R7m — AirNav Indonesia (@AirNav_Official) September 29, 2018

He stayed behind to make sure a passenger airplane safely took off, according to AirNav Indonesia, the agency that oversees aircraft navigation.

The current and former mayor of Palu are also among the dead, according to the the Red Cross.

An early tsunami warning had been issued by the Indonesian meteorological agency, but was later lifted after the agency ascertained that the water had receded.