Canadian Pacific says there is no indication that a freight train derailment east of Sudbury on Sunday poses a danger to the public or the environment.
CP spokesman Ed Greenberg says one of the rail cars derailed and as a result struck a trestle bridge near the community of Wanup.
Images of the scene showed the bridge collapsed and a number of cars carrying containers fell into the Wahnapitae River.
Greenberg says preliminary inspection of the containers indicates there are no materials or products that pose any danger.
He says roughly 24 containers were involved and there were no injuries in the mishap.
He says CP crews are working with local officials to determine the condition of the containers and which ones actually made contact with the water.
The initial investigation by CP has found one of the rail cars had an unexpected wheel bearing failure that caused the derailment just before the trestle bridge, Greenberg said in an email.
"Our early investigation indicates this incident is the result of an unexpected and catastrophic wheel bearing failure that could not have been detected in advance," Greenberg said.
Canadian Pacific has a network of electronic inspection systems that didn't detect any problem with the rail car wheels or bearings prior to the derailment, he added.
The Transportation Safety Board has dispatched a team of investigators to the scene to investigate the accident.