Heavy rain and flooding killed at least 16 people and left 10,500 homeless in the Solomon Islands' capital Honiara, with another 30 missing and the death toll expected to rise, aid workers said.
Entire communities were swept away as the city's main river, the Matanikau, burst its banks late on Thursday, bringing down bridges and inundating the downtown area in a disaster said to be one of the worst ever faced by the Pacific nation.
"This level of flooding is unusual. I’ve spoken to older people who lived on the island and they have said they’ve never seen anything like this before," Save the Children's Solomons head of logistics, Graham Kenna, told Al Jazeera.
Kenna also said that 16 evacuation points had been set up to shelter more than 10,000 homeless people, a huge proportion of the population in a city of only 70,000.
Fears of dengue fever was a major concern in the evacuation camps.
"Dengue fever was an already growing crisis here before the flooding. It is getting worse and worse and I predict that the fever will skyrocket when the place dries up," Kenna said. "We are trying to put in place and bring medical teams from Australia as there is only one hospital on the island where the capital is."
Tropical storm fears
The flooding followed days of heavy rain which was forecast to continue.
Some of my staff witnessed horrific things, especially the deaths of children and babies and it will take a long time, both for my team and the locals here, to recover from this.
Al Jazeera's senior meteorologist Everton Fox said the a low-pressure area could develop into a tropical storm.
"This slow-moving weather system has drifted slowly southwards across the islands dumping heavy and steady rain in the last few days," he said.
"The low is expected to strengthen as it moves into the northern Coral Sea and may eventually become a tropical cyclone in the process."
Sune Gudnitz, regional director of the the UN Office for the Coordination of Humanitarian Affairs (OCHA), told the AFP news agency that flood waters were continuing to build.
He said OCHA was ready to provide assistance but at the moment the Solomons' government was "firmly in the driver's seat" in the emergency response.
Kenna said 40 people were unaccounted for and chances of finding them would be slim. "No one goes missing in a situation like this and they have probably washed up into the sea," he said.
There was still virtually no information from the Guadalcanal areas outside the capital and it was likely communities elsewhere had also been severely affected.
Australia updated its travel advice for the Solomons warning of road closures and delays at Honiara's Henderson International Airport as well as advisory reports of looting in the city's Chinatown area.
New Zealand announced $257,000 in aid and said it was ready to provide further assistance if asked.
"The country is going to need a lot of assistance in the coming weeks. Some of my staff witnessed horrific things, especially the deaths of children and babies and it will take a long time, both for my team and the locals here, to recover from this," Kenna said.