Haiti’s earthquake struck shortly before 5pm local time on Tuesday afternoon, around 15 kilometres southwest of Port-au-Prince.
Witnesses reported people screaming “Jesus, Jesus” and running into the streets.
A five-storey UN building was reduced to rubble, with many casualties feared. UN peacekeepers have also perished.
The presidential palace now lies in ruins. President Rene Preval, who was not inside at the time, has called the damage “unimaginable.”
Fearful of fresh aftershocks, many people have fled outside the city, away from weakened walls.