A section of Canada's busiest highway has reopened after an early morning closure.

Ontario Provincial Police closed Highway 401 Eastbound between Gananoque and just west of Brockville for four hours following a series of overnight collisions.

In one crash, a tractor trailer was blocking the eastbound lanes just after County Road 2 in Lansdowne.

A Freezing Rain Warning was issued overnight for Ottawa and eastern Ontario. Freezing rain fell on parts of the region for several hours before changing to rain.