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 on Sunday for survivors of the tsunami that barreled ashore at about 9:30 p.m. on Saturday. Many Indonesians were at the beaches on western Java and southern Sumatra celebrating a long Christmas weekend.