Flash flooding killed at least six people and left 10,500 homeless in the Solomon Islands' capital, Honiara, yesterday, with another 30 missing and the death toll set to rise, officials said.
The government declared a state of emergency after the city's main river, the Matanikau, burst its banks late on Thursday, sweeping away entire communities, bringing down bridges and inundating the downtown area.
"This is the worst disaster the nation has seen," the Solomons Star newspaper said.
Save the Children's Solomons development programme director Rudaba Khondker described the situation as "dire".
"This level of rain has never been experienced before in Guadalcanal [the island where Honiara is located]," she said.
Khondker said 16 evacuation centres had been set up in local schools to provide shelter for 10,500 homeless people, a huge proportion of the population in a city of only 70,000.
"It's a logistical challenge," she said, adding that roads had been cut and communications were patchy. "The east side [of the city] is tough to reach and in the west side we're still carrying out assessments."
She said dengue fever, already common on the Solomons, was a major concern in the evacuation camps.
The National Disaster Management Office (NDMO) put the official death toll at six late yesterday, with another 30 listed as missing, although some reports said the number of fatalities had already reached 16.
"The figures, all the figures, are expected to go up," NDMO spokesman Sipuru Rove said.
He said the Solomons had declared a state of emergency but not yet asked for assistance from overseas, adding that such a request could be made at any time.
UN Office for the Co-ordination of Humanitarian Affairs' (OCHA) regional director Sune Gudnitz said the flooding followed days of heavy rain, which was still falling.
"The water has not subsided and floodwaters are continuing to build," he said. "The depression is threatening to turn into a category one cyclone in the coming hours and days."
Fiji-based Gudnitz 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.
Gudnitz said there was still virtually no information from areas of Guadalcanal outside Honiara, and it was likely communities elsewhere had also been severely affected.
Australia updated its travel advice for the Solomons, warning the flooding had closed Honiara's Henderson International Airport and cut roads throughout the capital.