Tens of thousands of BC Hydro customers remained without power on Vancouver Island Friday, the day after a storm wreaked havoc on B.C.'s South Coast.

The company said Thursday's storm, which left about 150,000 powerless on the island at its peak, "was one of the most severe storms BC Hydro has experienced in years."

Severe winds lashing the island and south coast caused "extensive damage" to electrical infrastructure, and crews will be working around the clock to repair it, BC Hydro said on its website.

"Due to the extent of the damage, many customers will be without power overnight and for some customers it could be days," the company said.

The western Vancouver Island communities Tofino and Ucluelet remained powerless into Friday. BC Hydro said a transmission line to the west coast was damaged in the storm and would need to be repaired.

"This is one of the worst storms we've seen on the island in a very long time," said BC Hydro spokesman Ted Olynyk. "In some areas, it's probably the worst storm we've ever seen."

Olynyk said at the peak of the storm, about one-third of BC Hydro customers on Vancouver Island were without power.

The widespread outages forced closures in the Nanaimo-Ladysmith School District at schools including Cedar Elementary and Secondary, Departure Bay Elementary, Fairview Elementary, Gabriola Elementary, Hammond Bay, Ladysmith Primary and Secondary, North Oyster Elementary, Rock City Elementary, Uplands Park Elementary and Wellington Secondary.

Only two schools in the Greater Victoria School District – Torquay Elementary and Shoreline Middle School – would be without power, but would remain open with a delayed start, the district said.

Eleven schools in the Cowichan Valley School District were without power and closed for the day, including: Lake Cowichan Secondary, Palsson Elementary, Chemainus Secondary, Chemainus Elementary, Crofton Elementary, Alex Aitken, Bench, George Bonner, Mill Bay Elementary, École Cobble Hill, and Thetis Elementary.

The wind also led to numerous injuries across the province. BC Emergency Health Service said paramedics responded to more than 20 patients who suffered wind-related injuries during the storm.

The storm also damaged a delivery system in the city of Nanaimo's water treatment plant, and as a result, the city is urging residents and businesses to conserve water until further notice. It has also closed pools and arenas until further notice. 

Power outages also led to a boil water advisory for residents of Salt Spring Island. The Capital Regional District is asking residents on Sky Valley Road and Lord Mike's Road to boil their water vigorously for at least one minute until further notice.

Toppled trees and surges of floodwater caused major damage to Vancouver Island highways, with Highway 4 from Port Alberni to Tofino taking the brunt of the damage.

A washout between the Tofino-Ucluelet Highway and Taylor River Rest Area has forced single-lane alternating traffic on the highway for a 0.5 kilometre-stretch.

The storm also caused a fatality in Duncan, where a toppled tree struck and killed a woman. The BC Coroner's Service is investigating.