Several fuel tankers have caught fire at a truck park near the western Iranian city of Kermanshah, sparking panic among local residents.
Governor Fazlollah Ranjbar was quoted by the official IRNA news agency as saying that the fire broke out on July 28 during repair work to a heavy vehicle before spreading to seven others.
The governor, however, denied there was an explosion.
"We did not have any explosions anywhere in the city today and the black smoke that citizens see in the sky of Kermanshah metropolis was related to the fire in this truck park," Ranjbar said.
The blaze was contained by firefighters and rescue efforts were still ongoing, he added.
Five people including four firefighters were injured, an emergency services spokesperson told French news agency AFP.
The tankers did not belong to the Oil Ministry but to a private company, according to local authorities.
The incident is the latest in a string of unexplained explosions and fires at military and civilian sites across Iran in recent weeks.
Two explosions hit Tehran late last month, one near a military site and the other in a health center, the latter killing 19 people.
Fires or blasts also rocked a shipyard in southern Iran and the Natanz nuclear complex in central Iran this month.
Officials said the Natanz fire was an accident, before adding they would not reveal the cause for "security reasons."