Ontario's provincial utility says power has been restored to more than half a million customers four days after an ice storm first moved into the region, but that some hard-hit areas may remain without it until the end of the week.

Some Ontario regions hard hit by last weekend's ice storm may not recover power until the end of the week, Hydro One said Tuesday as crews and communities braced for more freezing rain in the coming days.

Burying electrical wiring is more common in dense urban areas such as Toronto, but that doesn't mean they're immune to weather-related outages.