NZ and Australia sent surveillance flights to Tonga, the only way to figure out what happened after a tsunami cut off internet and phone access

• A tsunami hit the Polynesian island nation of Tonga on Saturday, knocking out its communications.
• Australia and New Zealand sent flights to assess the damage.

Australia and New Zealand have sent surveillance flights to the Polynesian country of Tonga to try and figure out what happened after a tsunami hit its islands and knocked out communications.

An underwater volcano erupted near Tonga on Saturday, triggering a tsunami. There have been no reports of mass causalities, but officials have warned that the impact isn't fully known because communications were hit.

The New Zealand Defense Force tweeted that an Orion aircraft had left for Tonga on Monday "to assist in an initial impact assessment of the area and low-lying islands."

It also said it was ready to deliver aid.

Zed Seselja, Australia's minister for the Pacific, tweeted that a "P-8 surveillance flight has departed to Tonga this morning to assess the situation on the ground."

"Australia stands ready to provide every possible support to the people of Tonga following the devastating tsunami."

Katie Greenwood, the Pacific head of delegation for the International Federation of Red Cross, told Reuters that up to 80,000 people may have been affected. A British woman has also been reported missing.

Officials in Tonga said drinking water and food were urgently needed, CNN reported.

Seselja said there was "significant property damage" and there was "very limited, if any" information coming in from the country's outer islands, CNN reported.