A worker was killed in a crane accident at an oil well site in western North Dakota, the Occupational Safety and Health Administration said Tuesday.

The incident, which happened late Monday near Ross in Mountrail County, was the second oilfield-related death in North Dakota's oil patch in the past week, the federal agency said.

OSHA spokeswoman Rhonda Burke said the 36-year-old man died after being "stuck by the boom" of a crane. The agency said he worked for Advance Energy, a South Boardman, Michigan-based drilling contractor. The man's name was not immediately released pending notification of relatives.

A man who answered the phone at the drilling firm's headquarters Tuesday would not confirm the death but said a company official was en route to North Dakota.

Eric Brooks, director of OSHA's office in Bismarck, said a five-member crew was using the crane to take pipe out of the ground and replace a tool that was about 650 feet underground. The worker was struck in the "upper torso" and killed by the crane's boom as it was lowered, he said.

The oil well is owned by Houston-based EOG Resources Inc., Brooks said.

OSHA also is investigating the cause of an explosion and fire at an oil well near Watford City on Saturday that killed a man and seriously injured two others. The McKenzie County Sheriff's Department said 52-year-old Johnny Stassinos of Rock Springs, Wyoming, died Saturday afternoon from injuries suffered that morning at a well site operated by XTO Energy Inc. near Watford City.

Officials said Daniel Montes, 28, of Fruita, Colorado, and Richard Maheu, 27, of Rock Springs, Wyoming, were airlifted to the Regions Burn Center in St. Paul, Minnesota, where they were listed in critical condition.

The men suffered third-degree burns to 70 percent of their bodies, Brooks said.

Authorities said 40-year-old Justin Pyle of Grand Junction, Colorado, was treated for minor burns to his face at a Watford City hospital and later released.

OSHA said the latest death brings to 50 the number of oilfield-related fatalities in North Dakota since late 2010.