TORONTO -- Environment Canada says a preliminary investigation has determined a tornado hit an area northwest of Toronto.

The weather agency sent an investigator to the scene Friday morning after a night of high winds in central Ontario left some damage in the Shelburne, Ont., area.

Environment Canada meteorologist Geoff Coulson says the surveyor who went to the scene will be continuing his investigation Friday and will have to confirm his findings later in the day.

Coulson says the preliminary estimate is that winds were between 135 and 175 kilometres an hour, making it a "One" on the enhanced Fujita scale.

He says that would put the tornado on the lower end of the scale used by the weather agency to categorize tornadoes, since EF-Zero is the weakest event and EF-5 is the most powerful.

The roof of a barn about five kilometres northwest of Shelburne was torn off and thrown about 150 metres during the windy evening and the side of another barn was sheared off seven kilometres west of the community.

In the Town of East Gwillimbury, meanwhile, police say about 20 hydro poles were knocked down on Woodbine Avenue (between Green Lane and Garfield Wright Boulevard.)

York Regional Police say the affected area will be closed to traffic for two or three days.

Environment Canada says a sharp cold front accompanied by showers will cross southern Ontario on Friday and strong westerly winds were expected to persist for several hours before abating in the evening.