A Canada Post driver was nearly hit after a chunk of ice fell 40 storeys and came crashing through the roof of his truck.

The postal worker told CTV Toronto that he had just stepped out of his truck on a downtown street when the block of ice fell from a condo building and ripped through the top of his vehicle.

"If it had hit him it certainly would have done possibly a critical injury,” Stephan Powell, district chief with Toronto Fire Services, told CTV Toronto.

Locals counted their blessings as they observed the damage.

"I woke up at about 2 o’clock to some crashing ice on our balcony and it scared us," local resident Kathleen Willmetts told CTV.

As temperatures rise, residents are being warned to look up and be wary of falling ice.

"Be vigilant, look up, if you see something that looks dangerous try not to walk underneath it,” Powell said.