Watch: Indonesian band loses drummer, guitarist as tsunami engulfs gig

Partygoers screamed as tsunami waves smashed into a beachside concert in Indonesia, sending band members tumbling off a collapsing stage, dramatic video footage showed on Sunday.

Some 200 employees of state electricity utility Perusahaan Listrik Negara (PLN) and family members had gathered at the Tanjung Lesung beach for an end-of-year party when the tsunami struck on Saturday night.

Video footage shared on social media showed partygoers enjoying the music and then screaming as the waves crashed into the stage and band members were swept away. Reuters was not able to immediately verify the video.

"Underwater I could only pray 'Jesus Christ help!'," Zack, a crew member of the rock band Seventeen, said in an Instagram post describing how he struggled in the water.

"In the final seconds I almost ran out of breath," he said, adding he survived by clinging to part of the collapsed stage.

At least 168 people were killed and hundreds injured by the tsunami, triggered by an underwater landslide after the eruption of the Anak Krakatau volcano, and the death toll is expected to climb.

Among the dead were four members of Seventeen - bassist M.

Awal "Bani" Purbani, road manager Oki Wijaya, guitarist Herman Sikumbang and crew member Ujang, the band said.

The band's drummer was missing.

"Lost Bani and our road manager Oki," lead singer Riefian "Ifan" Fajarsyah told followers in a tearful recorded video message on his Instagram account.

At a news conference, PLN said 29 employees and relatives had died and 13 were missing.

Survivors were treated at clinics but could not return to Jakarta because road access was blocked, Yulia Dian, a manager for the band in Jakarta, told Reuters by telephone.

"We were shocked because a lot of the people who went there took their families," Dian said, noting the band had been due to return to Jakarta on Sunday.

"They'd been sharing stories they were having fun at the beach and we didn't expect this."