MUNDA, Solomon Islands — Men perched on rocks peered out to sea through binoculars at a camp near the Solomon Islands town of Munda on Wednesday, watching for another deadly wave.

The camp is one of many that have sprung up in hills behind towns hit by Monday’s tsunami and earthquake. With strong aftershocks still jolting the region, the 40 families huddled there were afraid to come down, though some had run out of water.

“There’s no water to wash, no water to drink,” said Esther Zekele, who fled with her husband and five children to the camp on Monday as the sea surged into Munda, on the western island of Gizo.

On Wednesday, they ventured back for a sack of rice to replace the one they brought with them, now half gone. But when they heard a rumor that another wave was coming, they took to the hills again.

The fears of another tsunami have made it difficult for officials to determine the number of victims and get aid to the homeless. And aftershocks were pushing some survivors even deeper into the hills.

“People are in a panic because of the continuous tremors,” said Rex Tara, a disaster management specialist with British-based aid agency Oxfam.

At least 28 people were killed by tsunami and magnitude-8 earthquake and authorities were checking unconfirmed reports of further deaths, including six people buried in a landslide on Simbo, another island in this South Pacific nation.

Authorities have no firm figure for the missing, but Solomon’s deputy police commissioner Peter Marshall said aerial surveillance flights in the past two days had revealed “was no evidence of mass deaths.”

Red Cross official Nancy Jolo said her agency had handed out all the emergency supplies it had stored in Gizo, the main town in the disaster zone, and was waiting for new supplies from a New Zealand military transport plane that landed late Tuesday in Munda.

“The priority need right now is for water,” Jolo told Australian Broadcasting Corp. radio. “What we are experiencing right now in some of the campsites is children starting to experience diarrhea.”

Six doctors and 15 nurses from Honiara were among aid workers who arrived Wednesday at Gizo, where the airport remained closed and the wharf was badly damaged.

Many of the 5,600 left homeless were left scrounging for basic supplies under buildings knocked down by the quake and sludge deposited by the tsunami.

One police patrol boat arrived in Gizo on Tuesday after traveling 10 hours from the capital, Honiara, with tents, tarps, food and water. A second supply boat left Honiara on Wednesday evening, but two others were delayed because provisions could not be found to fill them, chief government spokesman Alfred Maesulia said.

“It’s very difficult to get the materials needed because Honiara only has very small shops,” he told The Associated Press.

A New Zealand military transport plane unloaded a shipment of tarps, water and rations at Munda.

“We have not reached people as soon as we could ... because of the widespread nature of this particular disaster,” said Fred Fakarii, chairman of the National Disaster Management Council.

Many canoes and other boats were sunk or washed away by the tsunami and fuel was contaminated with sea water, adding to the aid delivery woes.

Fakarii said officials had asked for two mobile hospitals from Australia and New Zealand. Hospitals at Gizo and Munda had been wrecked by the disaster, he said.

The quake, which struck 6 miles under the sea about 25 miles from Gizo, set off alarms from Tokyo to Hawaii, testing procedures put in place after the 2004 Indian Ocean tsunami that left 230,000 dead or missing in a dozen countries.

Gizo’s proximity to the epicenter meant the destructive waves — up to 16 feet high — hit before an alarm could be sounded, rekindling debate about whether the multimillion-dollar warning systems installed after the 2004 tsunami are worth the cost.

No significant tsunami was reported outside the Solomons, which are comprised of more than 200 islands with a population of about 552,000 people.