ST-LAZARE, Man. -- Canadian National Railway says it doesn't yet know how much oil leaked from a derailment in western Manitoba, but it says trains are now running on the line again.

The railway said Saturday there was "a partial leak" of crude south of St. Lazare, Man., but it was contained and none had reached a nearby river.

When asked on Sunday about how much oil spilled, and how many of the 37 cars that derailed on Saturday leaked, a CN spokesman said it's "still being assessed.

"Several of the cars were leaking but the product has been contained and has not entered the Assiniboine River," Jonathan Abecassis said in an email.

Abecassis said CN's environmental experts have begun the cleanup.

Transportation Safety Board spokesman Alex Fournier said investigators from the board spent Sunday at the site, but he didn't have information about the quantity of the spill either.

He said he expected further information would be available on Monday.

Barry Lowes, reeve of the Rural Municipality of Ellice-Archie, Man., which surrounds St-Lazare, said Saturday that "quite a bit" of oil had spilled and there was a foul smell in the area.

CN said no one was injured in the derailment and there was no fire reported.

The Manitoba government said in an email Sunday that a number of provincial agencies were responding to the derailment, but that CN is leading the cleanup.

"While 37 cars have derailed, not all of them are leaking. There is no risk of contamination to the Assiniboine River," the government email said.

CN said the derailment is still under investigation.