Hundreds of people are missing feared dead after a quake measuring seven on the Richter Scale struck the Caribbean island yesterday.
Many buildings have been destroyed or badly damaged in the capital Port-au-Prince, including the presidential palace and the five-storey UN offices.
As darkness fell last night, fear of after-shocks led many people to spend the evening sleeping out in the open.
Jean-Claude Cerin, Tearfund's Country Representative for Haiti, who is based in Port-au-Prince is among thousands of people whose homes have been damaged or destroyed.
Rescue efforts to dig people from the rubble of smashed homes, shops and offices are being hampered by blocked roads, power cuts, disrupted communications and a lack of equipment.
As Tearfund partners in Haiti assess emergency aid needs, Jennie Evans, Tearfund's Head of Region for Latin America and the Caribbean, said, said, 'Although detailed information about the number of people needing help is proving hard to come by, it's clear that we are facing a very serious disaster.
'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.'
The UN has an 11,000-strong peacekeeping force in Haiti which is gathering information about the extent of the devastation.
UN Secretary General Ban Ki-moon said, 'My heart goes out to the people of Haiti after this devastating earthquake. At this time of tragedy, I am very concerned for the people of Haiti and also for the many United Nations staff who serve there.'