Relief workers rushed to deliver desperately needed food and water to survivors living on Vanuatu's outer islands, after a cyclone wiped out entire villages and flattened vast swathes of the South Pacific nation's landscape.
Teams of aid workers and government officials were planning to send a boat packed with supplies to hard-hit Tanna Island, where aerial assessments showed more than 80% of homes or buildings had been partially or completely destroyed by Cyclone Pam.
Lack of food was a growing worry for those who survived the storm, which packed winds of 168mph when it struck on Saturday.
"Everyone in Tanna and other islands in the south, they really live subsistence lives, so they grow what they need for a short period," said Tom Perry, spokesman for CARE Australia.
"And the reality is that much of that would have been washed away by this storm. That's a grave concern because we desperately need to get food to people soon."
Flyover crews who surveyed the outer islands saw a flattened landscape and widespread destruction, with survivors below trying to signal them for help, said Colin Collett van Rooyen, Vanuatu director for aid group Oxfam.
Teams of aid workers and government officials carrying medical and sanitation supplies, water, food and shelter equipment finally managed to land on Tanna and neighbouring Erromango Island yesterday, after being hampered in their efforts by poor weather and a breakdown in the nation's communications networks. The two islands were directly in the path of the storm.
An aerial assessment showed extensive damage on Erromango, with communities ranging from 70% to 100% destroyed on the archipelago's fourth-largest island.
On other islands, Mr Collett van Rooyen said plane crews saw people had made big, white "H'' marks on the ground in multiple villages, and people on Tongoa island flashed mirrors to attract attention.
Radio and telephone communications with the outer islands were just beginning to be restored, but remained patchy four days after Cyclone Pam tore through the islands.
Meanwhile, fears of a measles outbreak prompted aid workers to launch an emergency vaccination drive for children across Vanuatu, which has low rates of immunisation and already suffered one outbreak of the disease earlier this month.
Teams were travelling to evacuation centres and other storm-ravaged areas around Port Vila to vaccinate children, provide Vitamin A and hand out bed nets to help stave off mosquito-borne malaria, according to UNICEF.
The UN reported that 11 people were confirmed dead, including five on Tanna, lowering their earlier report of 24 casualties after realising some of the victims had been counted more than once.
It said 3,300 people were sheltering in dozens of evacuation centres on the main island of Efate and in the provinces of Torba and Penama.
Baldwin Lonsdale, Vanuatu's president, returned to his country from Japan, where had been attending a UN disaster conference when the cyclone struck.
"I trust the people of Vanuatu. I trust my government. I trust the people that they will stand united together as a nation and to rebuild the nation," he said.
Poor weather and communications issues have hampered relief workers efforts to reach the outer islands for days.
Most of the islands have no airports and those that do have only small landing strips that are tricky for large supply planes to navigate. On Efate, bridges were down outside Port Vila, impeding vehicle traffic.
Vanuatu has a population of 267,000 people. About 47,000 people live in the capital.