At least 18 people on a packed Carnival float in the Haitian capital were killed Tuesday when they were electrocuted by a power line.

A performer juggles machetes while standing on the top of his partner's head, during Carnival celebrations in Port-au-Prince, Haiti, hours before a tragic accident. (Dieu Nallo Chery/The Associated Press) 

The accident occurred as thousands of people filled the streets of downtown Port-au-Prince for the raucous annual celebration. People at the scene said someone on the float used a pole or stick to move a power line so the float could pass under it.

Some of the victims were instantly electrocuted in a flash of sparks, according to witnesses. Others managed to jump off, causing panic in the crowd.

"I saw the wire falling and sparks and I started running for my life," said Natacha Saint Fleur, a 22-year-old who was near the float at the time.

Dr. Joel Desire at the General Hospital, where many of the victims were taken, said at least 18 people died. It wasn't immediately clear if there were other victims taken elsewhere.

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