Hardline candidate Saeed Jalili and reformist Masoud Pezeshkian are in a close race in Iran’s presidential election.
The two candidates have been hovering around 40% of the vote, with more than 8 million votes counted, and each has overtaken the other in recent hours.
If neither Mr Jalili nor Mr Pezeshkian wins 50% of the vote, the election will go to a second round next Friday.
Unidentified gunmen attacked a vehicle carrying election boxes in Sistan-Baluchestan province, killing two members of the security forces, state media reported.
Pezeshkian, a former heart surgeon and health minister, promised a different approach, calling the actions of moral police enforcing a strict dress code on women “unethical”.
The vote was aimed at replacing former President Ibrahim Raisi, who died on May 19 when his helicopter crashed into a mountain, killing seven others.
Although Iran has 61.5 million eligible voters, turnout in this election is expected to be low. The index hit record lows during the congressional elections in March and the last presidential election in 2021.
Earlier unofficial estimates put turnout at just under 40% of all those eligible to vote, which if confirmed would be the lowest turnout for an Iranian presidential race since the 1979 Islamic Revolution.
The country’s supreme leader, Ayatollah Ali Khamenei, called for “maximum” turnout.
In 2022, 22-year-old Mahesa Amini was detained by the morality police for allegedly violating Iran’s strict clothing regulations. A wave of massive protests set off after her death shook Iran.
Human rights groups say hundreds have been killed and thousands detained in the crackdown.