Ontario's Ministry of Environment says some of the spilled crude oil from the rail cars that derailed near Gogama is pooling near the rail line and at the headwaters of a small, nearby creek.  

A CN spokesperson says the product has been contained in a slough at the site and has not entered nearby waterways or lakes. CN environmental teams are finalizing clean up plans and preparing to move forward with mitigation work.

CN has reported that 29 cars carrying crude oil from Alberta jumped the tracks late Saturday night. Seven of the cars caught fire at the site, about 80 km south of Timmins. Fires were still burning late Tuesday, but due to the extreme cold CN said the cars are being left to burn out.

The Transportation Safety Board said 15 cars were breached and are releasing oil at the train derailment site.

CN has boomed the nearby creek to prevent the oil from migrating downstream, said a spokesperson for Ontario's Ministry of Environment, adding the ministry has been on the site since the weekend ensuring the company is managing the situation properly. 

Dillon Daveikis of Sudbury flew over the site in a helicopter on the weekend.

"When the smoke cleared, you could see a tangle of railway cars and most of them were tanker cars that had been accordioned up to one another. And there was a spill off on the west side of the tracks​," she said.

Rob Johnston of the Transportation Safety Board of Canada said investigators don't yet know how much product has spilled. They're looking at a couple of clues about what might have happened, including a section of broken rail containing a rail joint, and also a broken wheel.

Johnston said there is no way to estimate how long the clean-up will take.

According to an email from CN, air monitoring shows there are no safety issues for the crews working in the densely wooded, remote area.

The derailment has also resulted in the cancellation of VIA Rail passenger service between Toronto and Winnipeg.

Both the eastbound and westbound Canadian trains are not operating.

VIA said service will resume once CN reopens the tracks where the derailment occurred.​