A Rosemount fertilizer plant remained shut down Wednesday while investigators probed an industrial accident that killed an Oklahoma truck driver and critically injured another as they loaded anhydrous ammonia on Monday.

The accident occurred at CF Industries' Pine Bend facility, which makes farm fertilizer.

The investigation reaches to Kingfisher, Okla., where worker-safety officials want to know whether the men's employer, a small trucking firm called High Pressure Transports, had properly trained the truckers to load and unload the poisonous compound.

Meanwhile, the parents of 31-year-old Robert Shue, who died at the scene, were making funeral arrangements in Kingfisher. Robert Shue hadn't discussed his training with his parents, but he was "mechanically inclined" when it came to doing that type of work, said his father, Claude Shue.

"He loved what he was doing," Shue said. His son had wanted to be a truck driver since he was in kindergarten, his father said.

"He was a happy-go-lucky guy, but he was a professional at what he did," Shue said. "I'm sure he knew what he was doing."

Evan Winters, co-owner of the firm, said Shue worked there for about a year. Winters said Shue and at least one other trucker had been in Minnesota for several weeks, picking up loads of ammonia in Rosemount and delivering them to sites for Crystal Valley Cooperative of Lake Crystal.

Winters said his firm had trained Shue and other truckers about hazardous materials. They included Roy Thomas Taylor, 56, who nearly died in the accident. Taylor remained in critical condition on Wednesday at Regions Hospital in St. Paul. A Dakota County sheriff's deputy, Rosemount police officer and fellow trucker pulled him 35 feet to safety.

"We're going to be talking to both companies involved -- the trucking company and the employer -- to review what safety and health training was offered to these employees either at the site or prior to the site," said James Honerman, spokesman for the Office of Safety and Health Administration (OSHA) in Minnesota.

In Rosemount, CF Industries has had no explosions, fatalities or other accidents that could result in such an inspection in the past five years, Honerman said.

Because anhydrous ammonia is hazardous, its transport is regulated by the U.S. Department of Transportation, said Michael Ritchie, hazardous materials specialist for the state Department of Transportation. The employer of truckers who haul hazardous materials must make sure they are trained and tested.

U.S. Department of Transportation records show High Pressure Transports has a satisfactory carrier rating. In the past two years, it has been forced to take three drivers out of service after 30 inspections of drivers, a rate higher than the national average. But its record on hazardous materials inspections has been spotless during that time.

At CF Industries, a spokesman said other truckers who were on the scene Monday reported that Shue was having trouble with a connection between a pipe delivering the ammonia and the tank on his truck. The high-pressure piping dislodged and the liquid rushed out and vaporized.

A CF employee saw the ammonia vapor cloud and within seconds hit a button shutting down the flow throughout the entire plant, said Brian Spencer, CF's general manager of distribution facilities.

Spencer said CF Industries has operated for more than 43 years without lost time because of worker injury.

The plant remains at a standstill during what would be its busiest time, with 24-hour operations, as farmers wrap up fall harvests.

Joy Powell • 952-882-9017