BRAMPTON, Ont. - CN Rail officials say a mechanical failure was the cause of a freight train derailment in Brampton, Ont., early today.

Twenty cars of the westbound train, which consisted of 150 freight cars, left the tracks on the CN main line just after 2 a.m.

CN regional manager Frank Binder says passenger and freight service is expected to be restored for the Thursday morning rush hour.

Binder says it appears the mechanical failure stemmed from parts that connected the cars.

There were no injuries reported, no evacuations required and police said there was no sign of a hazardous leak.

Binder says the rail cars were either empty or carrying general freight.

Due to the derailment, GO Transit cancelled all of its trains on the Georgetown line, except for two trains from Mount Pleasant and another from Bramalea.

Via Rail said its service between Toronto and Sarnia was also affected Wednesday, and alternate arrangements were made for passengers travelling to and from Stratford, Kitchener and Guelph.