One man was killed and another was injured Wednesday morning while constructing a major new power transmission line near New Prague, authorities said.

The Scott County Sheriff’s Office said the men were working on a cylinder of rebar when a strap broke, causing the rebar to fall a short distance and the men to fall into a 50-foot hole.

Robert Fenstermacher, 28, of Oologah, Okla., died at the scene from head injuries. Jeremy Moye, 37, of Machesney Park, Ill., suffered injuries to his extremities and was treated at Mayo One Hospital in New Prague and released. Both were employees of Aldridge Electric of Libertyville, Ill., a subcontractor on the CapX2020 power line project.

Jeff Arnold, corporate risk manager for Aldridge Electric, arrived at the accident site shortly after 4 p.m. Wednesday. He said both men have worked for the company for some time and both have families.

“The company feels horribly about this accident,” Arnold said. “We are trying to find out exactly what happened. That’s why I’m here. I’ll be reaching out to the families this evening and see what we can do to ease their grief, if you will, the best we can.”

“It’s just a tragedy,” he said.

Randy Fordice, a spokesman for Great River Energy, said crews dug the hole for the foundation of a power pole. The workers were wearing safety harnesses when the accident happened, he said. They were preparing for concrete to be poured into the hole.

The accident happened at 8:50 a.m. along County Road 2 between Drexel Avenue and Hwy. 21. OSHA inspectors were at the scene Wednesday afternoon, as well as representatives of Aldridge Electric and Scott County investigators.

The power poles are 140 feet tall, making it necessary to dig large holes filled with rebar and concrete to support them. Fordice said the foundation work has been suspended for a week while the accident is being investigated.

Fordice said workers have put in 500,000 man-hours on the CapX project so far with no work-loss hours until now.

On Monday, helicopters began stringing heavy-duty transmission lines; crews will install 250 miles of high-voltage line between Brookings County, S.D., and Dakota County. Wednesday’s accident did not involve that portion of the construction.

The $1.7 billion CapX project, being led by Minneapolis-based Xcel Energy and Great River Energy in Maple Grove and including nine other power companies, is one of the largest expansions of the power grid in state history. The utilities say it’s needed to serve a growing population that is consuming more energy than ever.