Gita, a category four storm, battered the island overnight and caused widespread damage, reports the BBC.
Electricity lines were downed and roofs were torn off houses by the high winds.
The government declared a state of emergency before the storm hit, and set up evacuation centres where thousands of people stayed overnight.
"The wind was terrifying. It was roaring overhead. We could hear roofs being lifted," a witness told Radio New Zealand.
The UK Met Office said the storm - which brought winds of more than 200km/h (124mph) - was the strongest to hit the main islands of Tonga since modern records began.
Tonga is made up of more than 170 islands, and is located in the Pacific Ocean east of Fiji and north of New Zealand.
Gita is expected to intensify into a category five storm - the highest level - on Tuesday as it moves towards Fiji.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
