DES MOINES, Iowa — Northwood, a tiny town 4 miles south of the Minnesota border, expected a blizzard Thursday, but not a plume and a boom that triggered a mass exodus.
The Iowa town’s 1,900 residents were asked to evacuate at about 9 a.m. in the wake of a fire with small explosions. Officials were concerned that a plume of smoke hovering over the fire might be laden with chemicals that could waft across rooftops and endanger the entire population.
Authorities said Thursday evening that there was not as much of a toxic threat as initially feared. Workers reportedly told officials there was sulfuric acid in addition to other chemicals, so an evacuation was prescribed for safety.
No serious illnesses or injuries had been reported by Thursday evening. The evacuation wasn’t mandatory, but most of the town’s residents fled to surrounding communities before getting an all-clear to return a little after 3 p.m.
“The reason we initiated the evacuation of Northwood was just precautionary measures,” said Mitch Hanson, first assistant chief for Northwood’s fire department.
The fire was at the Northwood Ag Products facility at the municipal airport on the east edge of the town.
The fire was not â€” as had been widely reported during the day â€” centered in a warehouse that contained sulfuric acid, a corrosive chemical that can cause tissue damage and severe burns. A warehouse with bulk chemicals is situated some 50 feet or more north of the shop, Hanson said, but it was untouched by the fire.
The fire ignited inside a shop, or machine shed, where the ag company primarily stored vehicles with a small amount of fertilizer. Three tanker trucks were parked inside the building, Hanson said, along with a forklift whose propane tanks might have been the source of the explosions reported by residents.
Nobody was inside the shop when it burned, Hanson said.
Four people sought treatment at Mercy Medical Center North Iowa in Mason City, officials there said. The patients’ specific symptoms weren’t available.
The cause of the fire remains under investigation by the state fire marshal’s office.
A company that specializes in air quality and residue tests also will be in Northwood on Friday, according to the local fire department.