"I'm not going to suppose to say what the cause was because we just don't know right now", he said. It was unclear whether the blast occurred in that part of the facility. Village of Cambria officials later said 17 were inside before revising the number back to 16. Eleven more were taken to area hospitals via ambulance and helicopter.
One plant employee is dead, two are believed missing and 14 were injured following an explosion Wednesday night at Didion Milling Inc.in Cambria, Wisconsin.
"The safety and security of our employees is our top priority", Clark said in a news release. An OSHA spokesperson said while they are working as quickly as possible, an investigation into the incident could take up to six months.
He says the cause of the explosion remains unknown.
In the last 35 years, over 500 grain dust explosions have been recorded at grain handling facilities in the US, killing more than 180 people and injuring more than 675, according to OSHA.
Forklift driver Robert Goodenow was one of the workers killed.
The Associated Press says OSHA cited the plant in January 2011 for "exposing workers to hazards associated with dust explosions". There's also an ethanol plant on-site, but it was not involved in the explosion.
The federal safety agency ordered the mill to correct the problem by April 2011, and the records show Didion paid a $3,465 fine and the case was closed in September 2013. OSHA hasn't cited the plant for anything since.
University of Wisconsin Hospital spokeswoman Emily Kumlien says five people were air-lifted to her facility. Four of the individuals are being treated at the UW Hospital Burn Center, and another is in intensive care at the hospital's Trauma and Life Support Center. She declined to disclose any of the patients' conditions.
"(The explosion has) impacted our operations but that's the least of our worries", he said.
He said the call came in around 11 p.m. and shook the community.
One worker was killed and two were believed missing Thursday, Richards said.
Some concrete storage silos are damaged but remained standing.
Students in Cambria returned to school Friday after it was canceled following an explosion at nearby Didion Milling. Clark said the possible causes for the blast were numerous.
The explosion occurred late Wednesday night at the Didion Milling Plant in Cambria, a rural village about 45 miles (72 kilometers) northeast of Madison.
Seventeen employees were working in the plant when the blast was reported at around 11pm on Wednesday, village officials said in a news release.
In this photo provided by Jeff Lange, firefighters work at the scene following an explosion and fire at the Didion Milling plant in Cambria, Wis., Thursday, June 1, 2017.
TV news vans lined the streets around First Presbyterian Church, where the Red Cross had set up a center in the basement, and dotted the parking lot of the single building that houses the Cambria-Friesland elementary, middle and high schools.
Cambria is approximately 70 miles northwest of Milwaukee.