The United Nations headquarters building in Port-au-Prince, MINUSTAH, has collapsed and many people are trapped under the rubble.
The building, located in Port-au Prince's former Christopher Hotel, is believed to have been on the path of the main earthquake.
Joining the Secretary General, several heads of UN agencies in New York, briefed the press on the situation in Haiti.
Alain Le Roy, head of Peacekeeping Operations confirms reports that many UN employees are missing.
"So far, there are still over 100 people unaccounted for and under the rubble. We don't know about their fate. Some people have been extracted out of the building but only less than ten for the time being. Some dead, some alive, so we don't know for the time being the fate of the other but of course we are extremely concerned".
Helen Clark, Head of UNDP, says 38 of her colleagues also went missing when their building collapsed.
An air reconnaissance over Haiti reports that many important buildings have collapsed, including the National Palace, the National Assembly Building, the Montana Hotel, where many UN staff were residing, and many government ministries and private residences.
Access to these places is difficult but the UN Peacekeeping Chief says engineers are hard at work trying to extract people from the rubble, using heavy equipment.
Alain Le Roy adds that some 3,000 peacekeepers are in Port au Prince securing the airport, port, main buildings and patrolling the area.
Jocelyne Sambira, United Nations Radio