Indonesia news websites described people running in fear from 5 metre waves after the tsunami hit at 9:30 on Saturday night.
Beaches in the Pandenglang District, South Lampung and Serang in the Sunda Strait between the islands of Java and Sumatra were the worst affected. Many of the dead were thought to be tourists, many from Jakarta.
Dozens of buildings were damaged, Indonesia's Disaster Mitigation Agency said. The death toll was likely to grow.
A spokesperson for the Department of Foreign Affairs and Trade told SBS News, "the Australian Embassy in Jakarta is making urgent enquiries to determine whether any Australians have been affected by the tidal wave that hit beaches in the Sunda Strait area".
Members of the Jakarta pop band Seventeen, who were performing at the Tanjung Lesung Beach Resort, are missing in the aftermath of the tsunami, Tribunnews reported.
An unverified photo of the tsunami.
Facebook - Øystein Lund Andersen
The Disaster Mitigation Agency said the tsunami was possibly caused by landslides from the Mount Anak Krakatau volcano and tidal waves due to the full moon.
"The two combinations caused a sudden tsunami that hit the coast," the agency said.
In a Facebook post, the agency said Pandenglang District, South Lampung and Serang were the hardest hit.
"Areas that were severely affected were ... Tanjung Lesung Beach, Sumur Beach, Teluk Lada Beach, Panimbang Beach, and Carita Beach," it said.
Norwegian volcano photographer Oystein Andersen was on the beach taking photos of the volcano after the earlier eruptions when the waves came.
"I had to run, as the wave passed the beach and landed 15-20m inland," Andersen wrote on Facebook.
"Next wave entered the hotel area where i was staying and downed cars on the road behind it. Managed to evacuate with my family to higher ground trough forest paths and villages, where we are taken care of (by) the locals. Were unharmed, thankfully."
Videos posted on social media showed flooded streets, an overturned car and people running up stairs to escape the waves.
