There were fears of further eruptions and warnings that the death toll could rise dramatically after the tsunami which struck tourist beaches and coastal areas around Indonesia’s Sunda Strait.

Officials said 222 people were confirmed dead and a further 843 injured after waves, thought to have been caused by underwater landslides triggered by a volcanic eruption, surged towards the coastlines of the islands of Java and Sumatra at about 9.30pm local time (2.30pm GMT) on Saturday.

Indonesia’s disaster management agency said 28 people were still missing and rescuers had yet to reach all the affected areas.

The worst-hit area was the Pandeglang area of Banten province in Java, the agency said.

Footage filmed on mobile phones showed the moment the tsunami hit beaches and residential areas in Pandeglang, sweeping people and buildings away. Rescue efforts continued as night fell on Sunday, but workers and ambulances were prevented from reaching some areas because roads remained blocked by debris.

Kathy Mueller from the International Federation of Red Cross and Red Crescent Societies told Agence France-Presse aid workers were helping evacuate injured people, bring in clean water and tarpaulins, and provide shelter.

She said the group was preparing for the possibility of diseases breaking out in the tsunami zone, adding: “The situation, and the death toll, will remain fluid over the next days and even weeks.”

The water washed away an outdoor stage where a local rock band, Seventeen, were performing, killing their bassist and manager. Other people who had been watching the band on the beach were missing.

“The water rose and dragged away everyone at the location. We have lost loved ones, including our bassist and manager … and others are missing,” Seventeen said in a statement.

In the city of Bandar Lampung in southern Sumatra, hundreds of residents took refuge at the governor’s office.

Muhammad Bintang, 15, who was at Carita beach on the west coast of Java when the wave arrived, described a sudden surge of water that plunged the tourist spot into darkness. “We arrived at 9pm for our holiday and suddenly the water came – it went dark, the electricity is off,” he said. “It’s messy outside and we still cannot access the road.”

The disaster agency said it was still compiling information on the tsunami’s impact and there was a “possibility that data on the victims and damage will increase”.

“Heavy equipment is being deployed to assist in evacuation and emergency repairs. BMKG [Indonesia’s Meteorology, Climatology and Geophysics Agency] and the Geological Agency are carrying out studies to ascertain the causes of the tsunamis and possible follow-up,” it said.

Authorities have told residents and tourists in coastal areas around the Sunda Strait to stay away from beaches, amid fears of further eruptions, and a high-tide warning will remain in place until 25 December.

The tsunami is believed to have been caused by undersea landslides that followed an eruption of the Anak Krakatau volcano. There were no significant seismic tremors to indicate a tsunami was coming.

Anak Krakatau, which is roughly halfway between Java and Sumatra, has been spewing ash and lava for months. The island volcano, whose name means child of Krakatau, is one of 127 active volcanoes along the length of the Indonesian archipelago.

It emerged from the ocean half a century after an eruption on nearby Krakatau in 1883. That eruption, thought to be one of the most violent volcanic events in recorded history, killed more than 36,000 people.

Ben van der Pluijm, an earthquake geologist, said the tsunami may have been caused by a partial collapse of Anak Krakatau.

“Instability of the slope of an active volcano can create a rockslide that moves a large volume of water, creating local tsunami waves that can be very powerful. This is like suddenly dropping a bag of sand in a tub filled with water,” he said.

Tsunamis caused in this way do not trigger alert systems and give authorities very little time to warn people of the impending threat.

Dr Simon Boxall from the National Oceanography Centre in the UK said: “There will be an outcry as to why an early warning system didn’t kick in. The same criticism was levelled after the September Palu tsunami, which killed 2,000 people.

“These tsunamis are very localised and to cover the Indian Ocean with sufficient sensors to warn against all such eventualities would require many thousand buoys on the network.”

The disaster agency said the size of the tsunami may have been exacerbated by an abnormally high tide because of the full moon.

A statement from the BMKG said: “The tsunami hit several areas of the Sunda Strait, including beaches in Pandeglang regency, Serang and South Lampung.”

Footage of the aftermath of the tsunami showed flooded streets and an overturned car. A spokesman for the disaster agency said 556 houses, nine hotels, 60 food stalls and 350 boats were known to have been damaged.

Øystein Lund Andersen, a Norwegian photographer who was in the area, wrote on Facebook that he was taking pictures of the volcano when he saw a big wave come towards him. “I had to run, as the wave passed the beach and landed 15-20m [metres] inland,” he said.

“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 through forest paths and villages, where we are taken care of [by] the locals. We’re unharmed, thankfully.”

Indonesia sits on the seismically active Pacific “ring of fire” and regularly experiences earthquakes and tsunamis. In September, more than 2,000 people were killed by a quake and tsunami that hit the city of Palu on the island of Sulawesi.

In 2004, a tsunami triggered by a magnitude-9.3 undersea earthquake off the coast of Sumatra killed 220,000 people in countries around the Indian Ocean, including 168,000 in Indonesia.