An Iranian ethnic Arab separatist Sunni militant group and Islamic State both claimed responsibility for that attack.
A suicide bomber killed at least two people and wounded many more outside police headquarters in the port city of Chabahar in restive southeastern Iran on Thursday, according to a revised official toll.
Chabahar city governor Rahmdel Bameri said earlier that four people were killed and many more wounded when the bomber blew up a auto, but later revised the death toll to two.
"The attacker set off the bomb as soon as he stopped outside Chabahar's police headquarters", Bamari said.
Mohammad Hadi Marashi, deputy governor for security affairs, told state television two police officers had been killed.
Sistan-Baluchistan province, where the bombing hit, has always been a flashpoint, with a number of attacks reported in recent past. There was no immediate claim of responsibility.
Videos posted online by Iranian news agencies, purportedly from Chabahar, showed thick smoke rising in the area after the blast.
The attack comes as Iran's economy reels in the wake of the USA re-imposing sanctions lifted by Tehran's nuclear deal with world powers.
Iran has stepped up security in border areas after gunmen in September opened fire on a military parade in Iran's southwestern city of Ahvaz, killing 25 people, nearly half of them members of Iran's elite Revolutionary Guards corps.
While rare, Iran has been targeted in recent years by militant attacks.
Reports say at least 19 people were also hurt, but Al Jazeera could not immediately verify the number of injuries.
Tehran often blames the United States, Saudi Arabia and Israel for backing groups to destabilize Iran, something its rivals deny.
Chabahar, near Iran's border with Pakistan on the Arabian Sea, is home to a new port recently built and is an economic free zone for the country.
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