March 16, 2015: Samuel, only his first name given, kicks a ball through the ruins of their family home as his father, Phillip, at back, picks through the debris in Port Vila, Vanuatu in the aftermath of Cyclone Pam. (AP)

AUCKLAND, New Zealand Relief workers saw a flattened landscape and widespread destruction in their first views of Vanuatu's outer islands Tuesday after struggling for days to assess the areas of the South Pacific nation hardest hit by a fierce cyclone.

Radio and telephone communications with the outer islands were just beginning to be restored, but remained incredibly patchy three days after Cyclone Pam hit. People were expressing their need for help any way they could: flashing mirrors or marking an "H" in white on the ground to signal planes that were surveying the outer islands.

Australian military planes that conducted aerial assessments found significant damage, particularly on Tanna Island, where more than 80 percent of homes and other buildings appeared to be partially or completely destroyed, Foreign Minister Julie Bishop said.

"We understand that the reconnaissance imagery shows widespread devastation," Bishop said. "Not only buildings flattened -- palm plantations, trees. It's quite a devastating sight."

Teams of aid workers and government officials carrying medical and sanitation supplies, water, food and shelter equipment managed to land on Tanna and neighboring Erromango Island on Tuesday afternoon, said Colin Collett van Rooyen, Vanuatu director for aid group Oxfam. The two islands were directly in the path of the storm, which packed winds of 168 miles per hour when it hit early Saturday.

An aerial assessment showed extensive damage on Erromango, with communities ranging from 70 percent to 100 percent destroyed on the archipelago's fourth-largest island. On other islands, Collett van Rooyen said plane crews saw people had made big, white "H" marks in multiple villages, and people on Tongoa island flashed mirrors to attract attention.

The destruction on Tanna was significantly worse than in the nation's capital of Port Vila, where Pam destroyed or damaged 90 percent of the buildings, said Tom Perry, spokesman for CARE Australia.

"The airport was badly damaged, the hospital was badly damaged but still functioning ... there's one doctor there at the moment," he said. "It's obviously a pretty trying situation."

The U.N. Office for the Coordination of Humanitarian Affairs reported that 11 people were confirmed dead, including five on Tanna, lowering their earlier report of 24 casualties after realizing some of the victims had been counted more than once. Officials with the National Disaster Management Office said they had no accurate figures on how many were dead, and aid agencies reported varying numbers.

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Cyclone flattened landscape in Vanuatu's outer islands