At least 20 people have died after a powerful cyclone struck Madagascar, says the disaster authority in the Indian Ocean island.

Cyclone Gezani made landfall on Tuesday, hitting the island's main port, Toamasina.

Madagascar's disaster management office reported that there was total chaos - with houses collapsing in the impact zone, where the bodies were discovered. Neighbourhoods were plunged into darkness as power lines snapped, while trees were uprooted and roofs ripped off.

Cyclone Gezani's landfall is likely to be one of the most intense recorded around the city in the satellite era, according to CMRS, a cyclone forecaster on France's Reunion island, cited by AFP.

The National Office for Risk and Disaster Management indicated that many fatalities occurred due to house collapses as the cyclone struck Toamasina - the country's second-largest city - with winds reaching 250 km/h (155 mph).

It's total chaos; 90% of house roofs have been blown off, entirely or in part, stated Rija Randrianarisoa, the head of disaster management at Action Against Hunger.

Madagascar's disaster management office has evacuated numerous injured individuals and hundreds of residents from a district around Toamasina, which holds a population of around 400,000.

Residents recounted the extreme conditions they faced when the cyclone hit. I have never experienced winds this violent... The doors and windows are metallic, yet they are being violently shaken, said local inhabitant Harimanga Ranaivo.

Gezani represents the second cyclone to strike Madagascar this year, coming just ten days after tropical cyclone Fytia claimed 14 lives and displaced over 31,000 people, according to the UN's humanitarian office.

In preparation for the cyclone, officials shuttered schools and hastily established emergency shelters.

By Wednesday morning, Madagascar's meteorological service reported that Gezani had weakened to a moderate tropical storm and moved inland, approximately 100 km (60 miles) north of the capital, Antananarivo.

Gezani will traverse the central highlands from east to west today, before moving out to sea into the Mozambique Channel this evening or tonight, the meteorological service advised.

Colonel Michael Randrianirina, the new leader of Madagascar who recently assumed power in October, was present in Toamasina on Wednesday morning to evaluate the aftermath.

The cyclonic season in the Indian Ocean around Madagascar typically lasts from November to April, with approximately a dozen storms formed annually.