KRISTEN GELINEAUMENTAWAI ISLANDS: Rescuers searching islands ravaged by a tsunami off western Indonesia raised the death toll to 343 Thursday as more corpses were wrapped in body bags or buried by neighbors. Officials said hundreds of missing people may have been swept out to sea. Elsewhere in Indonesia, the volcano that killed 33 people earlier this week began erupting again, though there were no reports of new injuries or damage. Mourners held a mass burial Thursday during a lull in Mount Merapi's rumblings. The twin catastrophes struck within 24 hours in different corners of the seismically charged region, severely testing the nation's emergency response network. Islanders dug graves and slung up tarps to sleep under in one of the hardest-hit areas, where a three-meter wave had swept houses off their foundations and deposited the shattered remains in the jungle. Many residents who fled to the hills were refusing to return home for fear the sea might lash out again. Officials say a multimillion-dollar warning system installed after a monster 2004 quake and tsunami broke down one month ago because it was not being properly maintained. A German official at the project disputed that, saying the system was working but the quake's epicenter was too close to the Mentawai islands for residents to get the warning before the killer wave hit. Search and rescue teams – kept away for days by stormy seas and bad weather – found roads and beaches with swollen corpses lying on them, according to Harmensyah, head of the West Sumatra provincial disaster management center. Some wore face masks as they wrapped corpses in black body bags on Pagai Utara, one of the four main islands in the Mentawai chain located between Sumatra and the Indian Ocean. Ferry Faisal, of the West Sumatra provincial disaster management agency, raised the official toll Thursday to 343 from 311 earlier in the day. He said 338 people are still missing. Harmensyah said the teams were losing hope of finding those missing since the wall of water, created by a 7.8-magnitute earthquake, crashed into the islands Monday. “They believe many, many of the bodies were swept to sea,” he said. On Pagai Seatandug island, the wave had deposited giant chunks of coral and rocks the size of people into the places where homes once stood in Pro Rogat village, one of the hardest-hit areas with 65 dead. Villagers huddled under tarps in the rain and talked about how many who had fled to the hills were too afraid to return home. About 1,300 kilometers to the east of the tsunami zone, Mount Merapi in central Java began spewing hot clouds of ash again at around 4:30 P.M. Thursday, according to the Indonesian vulcanology agency Subandriyo. Most residents have been evacuated from the area. It was unclear whether the new activity was a sign of another major blast to come. Tuesday's eruption killed at least 33 people and injured 17, said Agustinus, a doctor at the local health department. Thousands attended a mass burial for 26 of the victims six miles (10) kilometers from the mountain's base. They included family and friends, who wept and hugged one another as bodies were lowered into the grave in rows.