A powerful, magnitude 7.3 earthquake off the Haitian coast has rocked the capital and sparked a tsunami alert for states in the immediate vicinity.
Eyewitnesses in Port-au-Prince told the Associated Press a hospital and other buildings had collapsed and people were calling for help.
A visiting US official told the agency the sky was "just grey with dust" and he could hear distant screaming.
The impoverished state has been plagued by natural disasters.
Tuesday afternoon's earthquake was centred about 15km (10m) south-west of Port-au-Prince, according to the US Geological Survey.
It was quickly followed by two strong aftershocks of 5.9 and 5.5 magnitude.
The US Pacific Tsunami Warning Center said there was the possibility of a local tsunami that could affect "coasts located usually no more than a 100km [60 miles] from the earthquake epicentre".
A tsunami watch was in effect for Haiti, the neighbouring Dominican Republic, Cuba and the Bahamas.