Officials in Venezuela say gunmen fired at voters taking part in a referendum to decide if the President Hugo Chavez should remain in office.
One person died and 10 others were wounded in the attack when gunmen opened fire from motorbikes, 10 miles outside the capital, Caracas.
The attack came as voting was extended because so many people turned out to vote.
President Chavez urged Venezuelans to stay in the long queues that had formed in polling stations.
The former US President Jimmy Carter, who is in Venezuela to monitor the process, said it was the largest turnout he had ever seen.
The president's opponents called the referendum, accusing him of dictatorial behaviour and economic mismanagement.
But his supporters say he is the first leader to care about Venezuela's poor.
