The two members and two crew staff were killed after they were swept away when a wave crashed into the stage.
According to reports, more than 200 people have lost their lives as a result of the natural disaster, with others missing.
Seconds before the wall of water hit the stage, the video clip showed the audience, made up of some families, enjoying the performance by the band, ‘Seventeen’.
In an emotional post to his Instagram account, the band’s lead singer Riefian ‘Ifan’ Fajarsyah broke down as he told his 300,000 followers that his friends were missing.
Sadly, in a statement released by the group, it was revealed that Awal ‘Bani’ Purbani, road manager Oki Wijaya, guitarist Herman Sikumbang, and crew member Ujang, were found dead.
They also confirmed that two other band members and – reportedly – Ifan’s wife had still not been found.
The singer said: “(We) lost Bani and our road manager Oki.
“Andi (drummer) and Herman (guitar) and Ujang (crew) have not been found. Please pray so that my wife Dylan (Dylan Sahara) will be found soon.
“The rest are thankfully safe although suffering from injuries and broken bones. Please pray so my wife Dylan, Andi and Herman and Ujang can be found soon.”
According to reports, Ifan was swept out to sea before eventually being saved.
Speaking to local media, he described the total horror that he witnessed in the moments directly after the tsunami, and said the evacuation of the area is proving to be slow.
Ifan said: “Most of us, I and our manager are on the shore, including myself, when I was thrown into the middle of the sea, there were probably around 20 to 24 corpses around me.
“Evacuation is very slow because there are many roads cut off and bad weather, heavy rain.”
The band had been performing to around 200 employees of the state electricity utility Perusahaan Listrik Negara (PLN), while family members enjoyed a party on Tanjung Lesung beach, when the tsunami struck at about 9.30pm, on Saturday night.
Disaster agency spokesman Sutopo Purwo Nugroho apologised after initially saying the public should not panic as the wave was a tidal surge and not a tsunami, explaining there had been confusion because no earthquake had been recorded.
According to reports, the tsunami destroyed 430 houses, nine hotels and 10 ships, while so far there have been more than 200 people confirmed dead, and over 740 injured.
The natural disaster was the result of an underwater landslide, caused by the eruption of the Anak Krakatau volcano.