The Transportation Safety Board of Canada now is conducting an investigation into the rail-car runaway-incident last Tuesday night in Regina.
A railcar loaded with asphalt got away from workers and rolled between three and four kilometres across the city.
According to Cando Rail Services, the incident occurred when the railcar got away from workers for the contractor.
Cando handles railcar switching work at the Co-op Refinery Complex.
The car rolled south along CN tracks for between three and four kilometres.
It crossed Winnipeg, Broad and Albert Streets.
There were no injuries or spillage.
Cando said last week a preliminary investigation indicated the car had an air brake applied, but not a hand brake.
The company apologized to Reginans and said a full investigation is underway.
Cando did notify the Transportation Safety Board and CN, but not the City of Regina or its fire department.
Mayor Michael Fougere said he learned of the incident through media reports.