An Indonesian Christian aid group has sent a team to the Mentawai islands in West Sumatra, where an earthquake and tsunami have lead to the deaths of hundreds of people.

“It is estimated the death toll will continue to grow,” said the group, Yayasan Tanggul Bencana Indonesia, on its Web site. “Most of the victims are in South Pagai Island, which seems the most heavily affected.”

On Oct. 28, the group had reported at least 340 dead and cited officials who said it could climb to more than 500. Hundreds of people are missing and are thought to have been swept away by the powerful tsunami that followed the Oct. 25 earthquake.

The Indonesian archipelago sits on the Pacific Ring of Fire fault line, one of the world’s most active areas for earthquakes and volcanoes. Around 250,000 people were killed around the Indian Ocean when the same fault line triggered a massive tsunami in December 2006.

The YTBI belongs to the Geneva-headquartered ACT Alliance of churches and humanitarian agencies, including the Presbyterian Church (U.S.A.).

“Food supplies, clean water, shelter, clothing, medicines, blankets and medical teams are badly needed. Response is slow since the areas are isolated and can only be accessed by boat or helicopter,” said the ACT Alliance from Geneva.

The alliance is also responding to the effects of a volcano that erupted on Oct. 26 at Mount Merapi near Yogyakarta, as well as to people affected by the earthquake and tsunami.

It said the 7.7 Richter Scale earthquake hit the Mentawai Islands at 9.40 pm local time on Oct. 25 and that a total of 95 aftershocks have since been reported.

"The earthquake triggered a three meter-high tsunami with waves slamming inland about 600 meters and reaching the roofs of houses in the coastal villages on North Pagai and South Pagai Islands,” the ACT Alliance said on Oct. 28.

Staff of the YTBI and other ACT Alliance Indonesia Forum members Church World Service and the YAKKUM Emergency Unit arrived on Sikakap Island on Oct. 28 to conduct a joint assessment.

The YTBI had earlier reported that it had difficulty finding transportation to Mentawai.

The Rev. Parasoran Simanjuntak, chairperson of the Protestant Christian Church in Mentawai, reported that houses on the beach had been submerged by the waves. He said there were reports that Muntey Baraubaru village in North Pagai had been destroyed by the tsunami but that the bad weather meant it had not been possible to assess the damage. Several bridges on Sikakap Island have been cut off, he added.