JAKARTA, Indonesia — The rock band was playing its second song of a set when a wave nearly 10 feet high burst through a backdrop behind the stage, crashed into the drummer, his drum set and the other musicians, and swept the stage into the audience.
The group, Seventeen, reported that the bass player and the road manager had been killed, two of at least 281 people who died when a tsunami in Indonesia’s Sunda Strait struck without warning on the country’s two most-populous islands.
The band’s lead singer, Riefan Fajarsyah, fighting back tears in an Instagram post, said that his wife, two other band members and a crew member were missing, and a frantic search was underway Sunday for survivors of the tsunami that barreled ashore at about 9:30 p.m. Saturday. Many Indonesians were at the beaches on western Java and southern Sumatra celebrating a long Christmas weekend.
The band was performing at a gathering for families of employees of Perusahaan Listrik Negara, the state electricity company. Company officials said that 14 people attending the event had died and that 89 were missing.
More than 1,000 people were injured by the enormous wave, which also destroyed hundreds of buildings. Officials put the number of people still missing at 57.
It was the second deadly tsunami in Indonesia this year, and a devastating end to what was a horrific year for disasters in the country, with earthquakes, floods, fires and an airline crash that together have killed more than 4,500 people, the most in more than a decade.
Officials said they think that the tsunami was caused by an undersea landslide that was set off by volcanic activity on the island of Anak Krakatau. There was no seismic activity in the area, which might have prompted a tsunami evacuation alert and saved lives, the officials said.
The tsunami damaged or destroyed at least 611 homes, 69 hotels and villas, 60 small shops and 420 boats, said Sutopo Purwo Nugroho, the spokesman for Indonesia’s disaster management agency.
Sutopo noted that Indonesian officials were unable to detect the tsunami and provide a warning because “we do not have a tsunami early-warning system that’s triggered by underwater landslides and volcanic eruptions.”
“What we have,” he said, “is early warning based on earthquake as a trigger.” He added that the challenge is to develop a warning system that recognizes underwater landslides and volcanic eruptions.
But tsunamis triggered by earthquakes don’t always result in a warning, either. In the Sept. 28 earthquake and resulting tsunami that struck the city of Palu on the island of Sulawesi, no siren sounded. And some of the city’s largest residential areas were built atop land particularly at risk for liquefaction, when the shuddering of an earthquake transforms solid earth into a gelatinous gush. More than 2,100 people were killed in that disaster.
The area hit hardest Sunday was Pandeglang regency in Java’s Banten province, site of Tanjung Lesung Beach, where the band was performing. The area is popular with visitors from Jakarta, the capital. Videos and photos from Pandeglang showed extensive damage, with houses crushed and at least one car overturned.
One video showed a police officer rescuing a boy, 5, from a damaged home in Banten.
In a video posted on Twitter by Sutopo, search-and-rescue workers are shown pulling two bodies from rubble.
Officials said the road from Pandeglang to the nearby regency of Serang had been cut off, hampering rescue efforts. Dozens were also killed across the Sunda Strait in Sumatra.
In a Twitter post, President Joko Widodo expressed his “deep sorrow” for the victims and said he had ordered government agencies to search for survivors, recover bodies and care for the injured.
Indonesia, an archipelago of more than 17,000 islands, sits in an active volcanic and seismic area known as the Ring of Fire.
The Sunda Strait lies between Java, the country’s most-populous island, and Sumatra, the second-most populous.
The island of Anak Krakatau, or the Child of Krakatau, emerged nearly a century ago from the volcanic crater of Krakatau, which erupted in 1883 in one of the largest such events in recorded history.
The volcanic island has been growing steadily ever since, and in recent weeks has been erupting frequently. Officials said they would investigate whether volcanic activity had set off an undersea landslide that caused the tsunami.
“We don’t know what caused the tsunami yet,” said Rahmat of the meteorology agency. “We suspect it was caused by the Anak Krakatau activities.”
The biggest disaster to strike Indonesia in modern times was the Indian Ocean earthquake and tsunami that hit a dozen countries on Dec. 26 in 2004. In Indonesia, it obliterated much of the city of Banda Aceh, on the northern tip of Sumatra, and killed about 225,000 people.
In August, a 7.0 magnitude earthquake hit Lombok island, killing more than 550.
The death toll from disasters in Indonesia this year is the worst since 2005, when a 6.3-magnitude earthquake struck the city of Yogyakarta on Java island, killing more than 5,000 people.
This article originally appeared in The New York Times.