Col Ali Ghasempour, deputy police chief of the oil-rich Khuzestan province where Ahvaz is located, says the attack is under investigation.
The semi-official ILNA news agency says gunmen attacked a police station in Ahvaz today morning, setting off a shootout that also wounded four policemen.
None of the reports identified the gunmen, who managed to escape and were said to be at large.
Ahvaz was the scene of a series of deadly bombings and shootouts blamed on Arab separatists living in the region.