Thousands are feared to be dead after a 7.3 magnitude earthquake hit the Caribbean nation of Haiti on Tuesday afternoon, destroying buildings and wreaking havoc in the country's capital city of Port-au-Prince.

The quake is considered the strongest to hit the country in nearly a century, being called a "catastrophe of major proportions" by officials.

Historic buildings, including the presidential palace and the UN headquarters, were destroyed in the tremor, which hit on Tuesday at around 5 p.m. local time. Haitian President Rene Preval and his wife are reported as being safe and unharmed.

According to the US Geological Survey (USGS), 27 aftershocks hit the country just hours after the initial quake, leaving many on the streets for fear of more buildings collapsing.

While the number dead and injured remains unreported, officials estimate that tolls will be in the thousands.

Global responses to the tragedy have already been mobilized.

UK-based relief organization Tearfund dispatched nearly $80,000 on Wednesday to help provide living essentials for survivors.

"With so many buildings destroyed and so many people made homeless, the need for shelter and basic essentials such as food and water is extremely urgent," said Jennie Evans, Tearfund's Head of Region for Latin America and the Caribbean.

Also on site at the disaster is Catholic relief agency Caritas Internationalis who will be "providing support to survivors of the earthquake, such as food, shelter and comfort through churches and parish networks," according Humanitarian Director Alistair Dutton, who noted that there is a "strong Caritas presence in Haiti."

"A priority for Caritas will be to assess the damage and our local capacity to provide aid to survivors of the quake," Dutton said. "Caritas runs over 200 hospitals and medical centres in Haiti. It is experienced and prepared to respond to humanitarian disasters there as a result of the frequent hurricanes."

While Dutton is confident of Caritas' response capability, he also said that communications with relief workers has been difficult due to infrastructural problems in the country.

"Communications with our staff on the ground is difficult, but we are piecing together a picture of desperate need," he said. "Haiti is the poorest country in the western hemisphere. Conflict, recent natural disasters, and poverty has left Haitians with a weak infrastructure. Working in that environment will be difficult."

World Council of Churches (WCC) General Secretary the Rev. Olav Fyske Tveit issued a statement on Wednesday to give words of comfort for the victims of the tragedy.

"On behalf of the fellowship of churches of the World Council of Churches, I express our condolences and solidarity with the people of Haiti, as they once again experience the great burdens of anguish, damage, and death because of a natural catastrophe," Tveit said.

"They already have carried many burdens of political instability and poverty."