On Friday, September 28, a massive tidal wave unleashed by a 7.5-magnitude quake slammed into the Indonesian city of Palu located on Sulawesi island. The impact washed away Palu's 300-meter (328 yard) double-arched bridge, plunging cars into the water.

This satellite image from October 1 shows how Palu is built on lowlands at the end of a narrow bay. Scientists say the shape of the bay amplified the size and power of the waves by forcing the water into a narrow and shallow channel. The earthquake's epicenter was also located close to shore, making the waves more powerful and leaving little time for warning.

The wave hit Palu, a city with a population of 380,000, on Friday evening as Muslim worshippers were gathering for evening prayers in local mosques. Authorities said that many others were caught on the beach while preparing a festival which was set to start later in the day.

With local hospitals crowded by hundreds of wounded, doctors were forced to treat the injured outside. Komang Adi Sujendra, director of a Palu hospital, urged assistance. "We need all the help we can get," he said. "We need field hospitals, medical workers, medicines and blankets."

On October 2, the official death toll of the tsunami and quake reached over 1,200. Authorities expect that number to rise as more people remain trapped. On October 1, the national disaster agency told AP that over 150 bodies were buried in a mass grave, with the burial operations ongoing. Indonesia is a majority-Muslim nation, and religious custom calls for burial soon after death.

The tsunami carried sand, mud and debris inland. Roads were blocked and communications disrupted with other cities. Rescue efforts in remote areas around Palu was hampered by the extent of damage to infrastructure. More heavy equipment was also needed.

The heavy earthquake caused sand and silt saturated by water to take on liquid characteristics in a process known as liquefaction. The national rescue agency said that over 1,700 houses in the Palu area were wiped out by liquefied soil.

Authorities managed to open the local airport a day after the tsunami, allowing the Indonesian mlitary to start delivering aid. The country's President Joko Widodo (r) visited the island and pledged to rebuild the city. The Associated Press reported that Widodo has authorized international help. The EU and 10 countries including the US, Australia and China have offered assistance.

Indonesian media showed images of survivors entering the heavily damaged malls and supermarkets to loot supplies, despite the risk of building collapse. Some Palu residents started returning to their homes to salvage usable items. German news agency dpa reported on October 2 that police arrested 45 people in Palu for looting.

The earthquake and tsunami knocked out power to the island and left many residents without access to clean water and medical supplies. Some of them descended on gas stations to pump out fuel by hand for their generators.

President Widodo has opened the door to foreign aid organizations as 200,000 people remain in desperate need of food, water and medicine. International Search and Rescue (ISAR) Germany has sent personnel to assist authorities.

On October 11, authorities called off the search for missing people, leaving the whereabouts of around 5,000 people a mystery. Experts believe that many of the missing are buried underground after entire villages were swallowed by "liquid earth." To commemorate the missing, parks and monuments are planned for Balaroa, Petobo and Jono Oge, considered the worst-hit areas of the island.