Iran will hold a run-off election after hardline candidate Saeed Jalili and rival Massoud Pezeshkian, who is seen as reformist, both failed to secure a majority in the presidential race.
Candidates need to win 50% of the vote but the pair both hovered around the 40% mark - with Mr Pezeshkian finishing narrowly ahead.
Iran's interior ministry confirmed the second round is set for 5 July.
Two security force members were killed after unidentified gunmen attacked a vehicle carrying election boxes