PHOTOS: Significant damage as historic flooding grips Nova Scotia

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Significant flash flooding swept through communities near Halifax, Nova Scotia, on Friday evening after relentless tropical downpours dropped 150-200+ mm of rain on the area in just a couple of hours.

Rushing floodwaters inundated roads throughout the Halifax Regional Municipality (HRM), effectively cutting off access to some communities.

GET THE FORECAST: Maritimes face severe storm risk Saturday as floods hit Nova Scotia

"All residents asked to stay off roads and highways unless it's an emergency," provincial officials said in an emergency alert sent out on Friday night. Officials continued urging residents to stay home on Saturday as the region deals with persistent flooding and the threat for additional heavy rainfall.

Search and rescue crews continued to look for four people reported missing after their vehicles were submerged by floodwaters on Friday night, the government said in a press conference on Saturday.

THE LATEST: Four reported missing after historic Nova Scotia deluge

Significant and widespread road closures remain in effect across the HRM, with multiple roads and rail lines washed out by the flooding. The City of Halifax provided an interactive map of road closures throughout the HRM on its website.

A state of emergency remains in effect for multiple communities across Nova Scotia, including the Halifax Regional Municipality, freeing up resources to allow crews to respond to the flooding and its aftermath.

Historic rainfall totals

Widespread rainfall totals of 100-200+ mm fell across the Halifax area, with the heaviest rains hitting communities west and north of Halifax proper. An unofficial total of 251 mm of rain come out of West Bedford on Friday evening. Radar estimates show that some areas may have seen more than 300 mm of rain in just 4 or 5 hours.

Some of the heaviest rain fell over areas devastated by wildfires in late May and early June, which likely exacerbated the extent of the flooding in the affected areas.

These are unprecedented rainfall totals for the region, more akin to a heavy rainfall event you’d see somewhere like Florida instead of the Canadian Maritimes. For some perspective, Halifax typically averages about 95 mm of rain during the entire month of July.

A sizable plume of tropical moisture streaming into the region from the south fuelled the heavy rainfall. Persistent thunderstorms tapped into this moisture like a reservoir, efficiently wringing out copious amounts of water over the region.

Additional heavy rains are possible across Halifax and points east, with a renewed risk for thunderstorms covering the Maritimes on Saturday. Some of those storms could reach severe limits, bringing torrential rainfall to areas hit hard by Friday’s rains.

If you’re in the region, it’s safest to stay home until the rain stops and floodwaters have a chance to recede. Never attempt to drive across a flooded roadway. It’s impossible to tell how deep the water is until it’s too late, and the road may be washed out beneath the floodwaters. Only a small amount of moving water can strand a vehicle and even carry it downstream.

Residents across the area posted photos and videos of the flooding on social media on Friday evening. Check out some of the visuals from the area, below.

WATCH: Pouring rain drenches Halifax as storms tap into stifling humidity

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WATCH: How flash flooding occurs in urban areas

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