HONIARA, Solomon Islands - Some of the thousands left homeless by a tsunami ventured back into the devastated Solomon Islands town of Gizo today, picking their way through the ruins of stores in search of food and water.

But most were still too scared to leave the hillside where they have camped out since a powerful undersea earthquake sent waves up to 30 feet high crashing into several of the South Pacific islands.

At least 28 people in the Solomons died in Monday's tsunami and quake, measured at a magnitude of 8.1 by the U.S. Geological Survey. The victims include a bishop and three worshippers killed when a wave hit a church and a New Zealand man who drowned trying to save his mother, who remains missing.

Another five deaths were reported in neighboring Papua New Guinea, but those have not been confirmed.

Officials said the total was likely to rise once communication with surrounding villages on Gizo island is restored. They were also awaiting more detailed assessments of the situation on at least four other Solomon islands: Taro, Simbo, Choiseul and Ranunga.

Deputy Police Commissioner Peter Marshall said planes searching coastlines had spotted bodies but that these were in hard-to-reach areas.

“Some settlements have been completely wiped out by the waves,” Alfred Maesulia, a government spokesman in the capital, Honiara.

As many as 4,000 people were camped on a hill behind Gizo, said Alex Lokopio, premier of Western province, which includes the town of 7,000. Many were too scared to return to the coast amid more than two dozen aftershocks, including at least four of magnitude-6 or stronger.

The Solomon Islands Red Cross said about 2,000 Gizo residents were left homeless and that about 500 houses were destroyed, noting that “initial reports from other islands suggest similar or worse levels of damage.”

The Disaster Management Office said initial assessments indicate at least 916 houses destroyed nationwide and about 5,000 people affected.

TV footage taken by helicopter showed a muddy shore covered with flattened tin- and thatched-roof houses. Some buildings leaned awkwardly on broken stilts as men picked through the debris.

Lokopio said few of the homeless had even basic supplies, and that their situation would turn desperate within days without help. Danny Kennedy, a dive shop operator, said teams from the hillside camp had ventured into town looking for bottled water and other supplies - and found a mess.

“Unfortunately a lot of the stores, their cargo has fallen from the higher shelves and covered lower things, and the buildings are quite unstable,” Kennedy told New Zealand's National Radio.

Deputy police commissioner Peter Marshall said officials would tolerate survivors taking goods until emergency supplies arrived.

“They are desperate times in Gizo,” he said. “And we've got to be practical.”

A police patrol boat carrying emergency supplies arrived in Gizo from Honiara overnight and three private charters were due today. Australian and New Zealand military helicopters, part of an island security force, also were expected to assist with relief.

Three medical teams - six doctors and 13 nurses - were to fly to the region Wednesday morning from the capital. The teams were to set up medical centers at Gizo and the nearby town of Munda and on Taro island.

The quake struck shortly after 7:39 a.m. Monday (4:39 p.m. EDT Sunday) six miles beneath the sea floor, about 25 miles from the western island of Gizo, the USGS said.

The quake set off alarms from Tokyo to Hawaii, testing procedures put in place after the 2004 Indian Ocean disaster that left 230,000 dead or missing in a dozen countries.

But because of Gizo's proximity to the epicenter, the destructive waves hit before an alarm could be sounded.

“There wasn't any warning - the warning was the earth tremors,” Lokopio told New Zealand's National Radio. “It shook us very, very strongly and we were frightened, and all of a sudden the sea was rising up.”

Within five minutes, a wall of water up to 16 feet high plowed into the coast, inundating homes, businesses, a hospital, schools and two police stations, witnesses and officials said. Phone and power lines were downed, and the main airport damaged.

Maesulia, the prime minister's spokesman, told the Sydney Morning Herald that some coastal villages were struck by waves up to 30 feet tall, although most reported heights of between 9 and 15 feet.

Prime Minister Manasseh Sogavare declared a state of emergency and met with the impoverished country's aid donors.

“We were lucky it happened during the day time and the people observed that the sea receded and that that was a sign that something was not right and most people moved to higher ground,” Sogavare said.

More than 200 islands with a population of about 552,000 people make up the Solomon Islands. They lie on the Pacific Basin's so-called “Ring of Fire,” an arc of volcanos and fault lines where quakes are frequent.