As many as 46 CN Rail cars derailed Friday morning inside the rail tunnel under the St. Clair River.
Aamjiwnaang First Nation Emergency Planning said the derailed cars included two carrying automobiles on the Canadian side of the tunnel.
Diesel and motor fluids were impacting the inside of the tunnel, and there was a high concentration of CO detected.
Sarnia's Primary Control Group met at city police headquarters Friday afternoon and reported that one tank car containing sulphuric acid was breached in the tunnel but contamination was contained and environmental monitoring was continuing.
Aamjiwnaang said CN Rail plans to have the sump pits inside the tunnel collect any fluids, so they can be pumped out and collected in transportable tanks.
Sarnia Fire and Rescue Service spokesman Mike Otis said they responded at 5:30 a.m.
"Sarnia Fire Rescue is on scene, working with officials from CN and Sarnia police," said Otis. "We're there for safety purposes, there are no injuries to report and no off-site impact or public hazard at this time."
Officials also responded from the American side of the tunnel including the Port Huron fire department.
The Transportation Safety Board has deployed a team of investigators to the scene.
Further updates will be provided as they become available.
