American Samoa's acting governor Faoa Sunia has declared a state of emergency.
The American Samoa Governor, Togiola Tulafono, who is in Honolulu, says at least 24 people died after a series of waves smashed into the Samoa Islands, triggered by a magnitude 8 earthquake.
Samoa's disaster management office says up to 100 people may have been killed.
63 fatalities have been confirmed.
Tonga is sending a plane to its northern islands after reports that a tsunami may have killed ten people on Niuatoputapu.
The National Emergency management office's, Mafua Maka, says a tsunami may have hit Niuatoputapu, but they have had no contact with the island.
"At this stage, we have unofficially confirmed that ten people are missing on Niuatoputapu. Right now we have sent a plane, a charter flight, and they are assessing the situation from the air."
Mafua Maka says they also waiting to hear from the remote Vava'u and Happai islands.
Among the victims in the region are two South Koreans and an Australia while unconfirmed reports say a New Zealander has also been killed.
American Samoa's acting governor Faoa Sunia says initial reports from emergency response agencies list immense and wide-spread damage to individual, public and commercial buildings in coastal areas.
The US President Barack Obama has also acknowledged the situation and says a major disaster exists in American Samoa.
He has ordered federal aid to supplement territory and local recovery efforts.
Faoa Sunia says the emergency proclamation is issued to reduce the vulnerability of people to damage, injury and loss of life and property.
Faoa Sunia announced that electricity will be cut for several villages on the Eastern District on the main island of Tutuila.
He says he expects electricity will be down for a month and he has called for those in the Eastern District affected to make arrangements to live with families on Western side of Tutuila.
The waves that hit Pago Pago in American Samoa are said to have been up to five metres high.
Mike Sala, the director of American Samoa's office of homeland security, says power is completely off on the west side of the island
Some buildings were completely demolished by the waves, you know, there's no byuildings anymore except the foundation. This is in the village of Pago Pago. There is a two story building, the Pago plaza and the second floor was hit, so that estimated [the waves were] about 20 foot.
Mike Sala says he expects the number of dead to increase, but it will take some days to finalise.
In Samoa, teams sent out to provide emergency help on the southern coast of the island of Upolu have had to stop on the side of the road to provide help to those injured by the earthquake and tsunami.
The Chief Executive Officer at the Ministry of Health, Palanitina Toelupe, is at the main hospital and says people are being brought in as the roads are cleared:
For those that have come here to the main hospital, there are at least 15 inured people and 37 dead. The injured have been sent for teriary level care and at the same time where the response team of the police, the health as well as the Disaster Management Office staff have sent for the dead for identification and things like that.
Mrs Toelupe says the area is devastated and many families have relatives missing.
Reports are emerging of people trying frantically to escape the tsunami.
People on the south of Upolu had less than ten minutes to flee from enormous waves hitting the beachfront.
The Hotel Association's chief executive, Nynette Sass says people have escaped with only the clothes on their backs to a makeshift camp on higher ground.
She says the disaster will have a huge impact on the tourism industry.
It's somehow hard to take, the economic downturn and all this, and this was the one that Samoa was relying on, on tourism numbers. And with this devastation it's going to take, I don't know, quite a lot of money and time, let alone the dramatic things that the people have gone through. And it's not just the tourists, it's also our own people. Down the bottom as well on the seaside there's quite a few families as well with all their children gone, washed out. Some tried to escape in cars, and the waves got the cars. It's really heartbreaking.
A tsunami warning was in force for several hours across the Pacific Islands.
It caused alarm but most countries were spared devastation.
Late in the day in Samoa, there was another tsunami warning.
Police said they were responsible for a second alert in the capital, after another huge was believed to be approaching.
The alarm was cancelled and people were free to come down from higher ground.
Meanwhile, Kiribati now plans to re-open all schools and government offices tomorrow.
The secretary in the president's office, Betarim Rimon, says residents of the low lying country gathered at the stadium for safety, but most have now gone back to their daily lives.
We've sent all students home, all offices of government, including companies, they all closed down during the day and now we have delivered an announcement to the nation that Kiribati is now back to normal and all offices will open tomorrow as well as schools.
Betarim Rimon says they are still monitoring the situation and have advised residents to stay away from the beaches.
New Zealand's Red Cross is planning to send tarpaulins, water containers and first aid kits to Samoa to assist the victims of the earthquake and tsunami.
The organisation's international operations manager, Andrew McKie, says 130 Samoan volunteers are already on the ground to help the victims.
But Mr McKie says they need some assistance.
They have requested assistance with, firstly a person going over and help them take stock of the situation and assist with assessments along the southern coast. We're also deploying some emergency relief supplies, which is 500 tarpaulins, 500 water containers and 200 first aid kits.
Andrew McKie hopes the emergency supplies will be sent tomorrow.