Kaila White

The Republic | azcentral.com

Four people were burned Sunday evening in a grain-dust explosion at a Nestlé Purina plant in Flagstaff, authorities said.

Four contractors were doing welding work on the fifth floor of the plant, which is about 5 miles northeast of downtown Flagstaff, when dust produced during the food-making process ignited, according to Flagstaff Fire Department Capt. Bill Morse.

The explosion, which produced a brief fire, blew out several metal doors and burned all four contractors, who were sent to hospitals. One has severe burns, Morse said.

As of Sunday evening, one person was flown by helicopter and one was taken by ambulance to the Arizona Burn Center at Maricopa Medical Center in Phoenix, according to the department. The third was admitted to the Flagstaff Medical Center, where the fourth was admitted and later released.

Grain dust is the main source of fuel for explosions in grain handling, as it is highly combustible and can burn or explode if enough becomes airborne or accumulates on a surface and finds an ignition source such as welding, according to the Occupational Safety and Health Administration.

According to a Nestlé Purina website, the Flagstaff plant employs about 250 workers and produces 1,000 tons of dry dog and cat food a day.

The explosion caused a strange-looking cloud that was a combination of smoke and grain, Morse said.

No further information was immediately available.