A storm off the US coast of Northwestern and Western Canada is battering the region, bringing high winds, flooding and snow to more than seven million residents in states along the Pacific Ocean.

The storm caused major power outages and downed trees in buildings and roads.

At least two people in the Seattle, Washington, area have died after trees fell on them in separate incidents, police say. One woman was killed while showering at home, and another was killed in a homeless camp.

The ‘bomb cyclone’ – as forecasters call it – was caused by a rapid drop in air pressure off the coast, causing the weather system to rapidly intensify.

One woman died when a tree fell on a homeless encampment in Lynwood, north of Seattle, according to a social media post from the South County Fire Department.

Another woman in Kirkland was killed when a tree fell into her home while she was showering, according to the Bellevue Fire Department.

Officials say that when they arrived and confirmed the woman had died, “weather conditions were so dangerous in the area” that they were forced to transport the victim’s husband to a safer location.

Two other people were injured in Maple Valley, south of Seattle, after a tree fell on their trailer.

“It’s intense out there. Trees are down all over the city, and several are falling on homes,” the Bellevue, Washington Fire Department wrote in a social media post during the storm.

‘If you are able, go to the lowest floor possible and stay away from windows. Don’t go outside if you can avoid it.’

More than 700,000 homes and businesses in Washington were without power Wednesday morning, according to Poweroutage.us. Later in the day the number shrank to about 500,000. About 15,000 customers experienced outages in California.

Schools across Washington are closed Wednesday.

Pine needles, leaves and other storm debris covered the streets as the sound of chainsaws echoed in Issaquah, a city famous for its salmon farming in the foothills of the Cascade Mountains.

A man trying to reach his sister’s home in Issaquah, outside Seattle, told BBC News on Wednesday that it appeared as if a bomb had hit a nearby residential courtyard, which was littered with fallen trees.

In Northern California, the US Weather Prediction Center (WPC) said there was a high risk of excessive rainfall and warned of flash flooding and mudslides. Up to 8 inches of rain is expected to fall in San Francisco Bay.

The storm has also spread into Canada, where winds are the biggest concern and gusts of up to 100 miles per hour have been reported off the coast of Vancouver Island. About 140,000 customers were without power in British Columbia, according to the British Columbia Hydro and Power Authority.

BBC Weather presenter Stav Danaos said damaging winds will continue to diminish on Wednesday, although conditions are expected to remain stormy along the Pacific coast from San Francisco to Vancouver Island.

And incessant heavy rain is expected along much of the coast on Thursday and Friday, as a renewed ‘atmospheric river’ of moisture from the Pacific Ocean is pushed ashore.

In addition to wind, rain and snow, the storm could also cause flash flooding, rockslides and debris flows in high-altitude areas, as well as heavy mountain snow. The storm has already caused snowstorms in the Cascade mountain range, which runs through both the US and Canada.

The heavy, wet snow that has fallen on the Cascades and North Rockies will begin to thaw by the end of the week as milder air is brought in.

Snowmelt, combined with further heavy rainfall, is likely to cause severe flooding in places from Northern California to Oregon, with a significant risk of landslides by the end of the week.

Bomb cyclone is a term used by meteorologists for a storm that appears to be rapidly intensifying, with central air pressure dropping to at least 24 millibars within 24 hours.

They are called bomb cyclones because of the explosive power of these storms, caused by the rapid pressure drop.

The storm brings with it a range of weather conditions ranging from blizzards to severe thunderstorms to heavy precipitation.

These weather conditions are not unusual for this time of year.

Similar so-called atmospheric river events – when small pockets of moisture move outside of tropical regions – have occurred across North America in recent weeks.

But the conditions of an atmospheric river combined with a bomb cyclone can produce a major weather event.