While everyone in the area has moved to higher ground, there are fears that the water will return as a tsunami.
The quake struck at 6.48am NZ time and was centred 200 kilometres from Samoa's capital Apia at a depth of 35 kilometres.
Other villages reportedly with many deaths include Vailoa and Malaela in Aleipata - one of the worst hit villages.
Mrs Kupa said many people - although warned to stay inland - had gone to the southern coast of the island looking for loved ones feared swept away while out fishing.
"The radio is hot with calls from all over the island of reports of houses destroyed."
The West Coast/Alaska Tsunami Warning Center reported waves of 1.57m had been recorded at Pago Pago on American Samoa.
The waves that have caused destruction on Western Samoa's Upolu island were not as big, measuring about 0.7m above normal sea level.
A Radio Polynesia reporter told Radio New Zealand the south and south-east coasts of Upolu appeared to have been hardest hit.
"By the sound of some of the reports that have been coming in, it's not pretty at all," he said.
There were reports that low-lying parts of Monono Island, west of Upolu Island, had been underwater, he said.
Samoan journalist Cherelle Jackson said a full tsunami alert was activated about ten minutes after the quake.
All of the capital Apia has been evacuated to higher ground.
"All the schools, workplaces everyone has walked up - it's like a ghost town," she said.
There was a really good response from residents who had practised evacuation drills before she said "within minutes school children were walking up the hill".
Aftershocks are continuing to be felt.
New Zealanders John and Grace Winther are holidaying in Apia and told nzherald.co.nz sirens started going off shortly after this morning's earthquake.
They went outside but found everyone else staying at their hotel had already gone, so waved down a passing policeman who took them to a school on higher ground.
They later discovered the man who had assisted them was the assistant police commissioner.
The
Samoa Alive
news website is reporting that products were thrown off shelves in supermarkets in Apia.
It also reports high seas hitting coastal areas around Fagaloa and Siumu on the eastern side of Upolu Island.
"Long streams of cars are jamming the roads and it maybe a while for traffic officers to untangle the road jams," it said.
New Zealander Scott Mulholland, who works for a communications firm in Apia, told Newstalk ZB everyone had fled.
He said the evacuation was speedy thanks to the fact that police are on duty at every major intersection at the moment because of the driving change-over from the right to the left hand side of the road.
A resident of a coastal village, Theresa Fanene Duffy, told Radio New Zealand her house has been destroyed by the tsunami, as were houses and cars in a neighbouring village.
"We are still on Mt Vaea, we are still being told to stay put," she said.
"We lost a home already... our neighbouring villages, there are about three kids that have already been taken by the tsunami," Mrs Duffy said.
A four-year-old kid from Manono has been taken by the tsunami."
Mrs Duffy says she heard on the radio that a boat that was on the water at the time of the tsunami was "squashed" by the waves and that the four-year-old cannot be found.
A number of Australians have been injured in the aftermath of this morning's earthquake and tsunami, the Federal Government said.
"The early reports don't suggest that any of them are very serious, but they are in hospital," parliamentary secretary for international development assistance Bob McMullan told Sky News.
Australian consular officials in Samoa were at local hospitals to offer assistance, he said.
- with NZHERALD STAFF, NZPA, AP, AAP
