At least 222 persons were killed and 843 injured after a tsunami struck without warning in areas around Indonesia’s Sunda Strait on Saturday night, Reuters reported, quoting the country’s disaster agency. Aroun 28 people are missing, and hundreds of homes have been damaged.

Search and rescue teams are looking for survivors under debris, the agency’s spokesperson Sutopo Purwo Nugroho said.

The tsunami struck coastal areas between the Sumatra and Java islands about 9.30 pm local time (8 pm Indian time) on Saturday, Reuters reported. The country’s geological agency is working to ascertain the cause of the unexpected tsunami, Nugroho said. The toll is likely to rise. Heavy equipment is being taken to badly-hit areas to help search for victims.

Early reports indicated that the tsunami may have been caused by an abnormal tidal surge due to the new moon and an underwater landslide following the eruption of the volcano Anak Krakatoa, according to AFP. The Anak Krakatoa is known as the “child” of the Krakatoa, whose eruption in 1883 had killed 36,000 people and had sparked a tsunami that was felt around the world. The Anak Krakatoa is a small island in the Sunda Strait.

Nugroho also apologised for an initial message that the wave was not a tsunami. The authorities had said it was a tidal surge and urged the public not to panic. Nugroho later said it had been difficult to ascertain the cause initially as there had been no earthquake. “If there is an initial error we’re sorry,” he said on Twitter.

Residents and tourists in coastal areas around the Sunda Strait have been warned to stay away from beaches and a high-tide alert was issued until December 25. “Those who have evacuated, please do not return yet,” said Rahmat Triyono, an official at the Meteorology, Climatology and Geophysics Agency, according to Reuters.

Television footage showed the moment when the tsunami hit an event where a popular Indonesian pop group “Seventeen” was performing. “The water washed away the stage which was located very close to the sea,” the band said in a statement. “The water rose and dragged away everyone at the location. We have lost loved ones, including our bassist and manager ... and others are missing.”

This is the second tsunami to hit the country in three months. A 7.5 magnitude earthquake had struck off the Sulawesi island in September and caused a tsunami, killing hundreds of people. A series of earthquakes in July and August had killed nearly 500 people on the holiday island of Lombok.