Sgt. Matt Johansen says that the Occupational Health and Safety Administration is investigating.
Authorities say a 49-year-old Duluth, Minn., man has been killed in a hydraulic fracturing accident in North Dakota.
The McKenzie County Sheriff's Office says Mike Krajewski died about 3:30 p.m. Saturday at a Halliburton location about 24 miles north of Watford City.
Sgt. Matt Johansen tells The Forum (http://bit.ly/11Lus3l) that the Occupational Health and Safety Administration is investigating. He says preliminary information indicates a valve was turned wrong and a pipe came disconnected and hit him in the head.
A Halliburton spokeswoman says the company will continue to work with local authorities as they investigate the incident.
Another worker was hospitalized for injuries believed to be minor.
Relatives say Krajewski was a family man and Air Force veteran who was proud of the work he was doing.