A power line has fallen on a float during the annual Carnival celebration in the Haitian capital, killing multiple people.

Witnesses say about 20 people may have been killed in the accident. It occurred before dawn Tuesday as thousands of people packed the streets of downtown Port-au-Prince for the raucous celebration.

Authorities were responding to the scene and it was not immediately possible to get an official casualty figure.

People at the scene said the accident occurred when someone on the packed float had used a stick or a pole to move a power line. Some managed to jump off the float and escape, sparking panic in the crowd.

Hundreds of people thronged the General Hospital, some carrying victims and others searching for family members brought by ambulance.