Security forces in Guyana say a boat carrying election officials and ballot boxes was shot at "from the Venezuelan shore" in the contested Essequibo region.
Police and the Guyana defence force said in a joint statement that the incident occurred on Sunday, ahead of the South American nation's general election on Monday.
The patrol that had been escorting the officials "immediately returned fire" and no one was injured, Guyana's security forces said.
Venezuela has not commented on the incident, which comes amid a territorial dispute between the two nations over the oil-rich Essequibo region.
The 159,500-sq-km (61,600-square-mile) area has been administered by Guyana, and British Guiana before it, for over a century.
