At least four people died when armed men attacked an office in Abidjan, run by supporters of opposition leader Alassane Ouattara.
The attack came despite a night-time curfew and army and UN troops patrolling the streets.
A man said the gunfire started at around a quarter to nine and lasted for around half an hour. After they had killed the people they climbed over the wall to get in here. They threw tear gas so no one could see what was going on. When they had finished killing, they left.
On Tuesday, a representative of incumbent President Laurent Gbagbo tore up the initial results before they could be announced.
Opposition supporters say Gbagbo is trying to block the announcement because he knows he has lost.
The poll is the first in Ivory Coast for ten years. The country has been divided since a civil war in 2002.
The poll is meant to unify the two different camps – but some say it has merely served to highlight the differences.