Roughly 10 percent of Hawaii Island residents still do not have power as a result of storm-related damage and some may need to live without electricity beyond this week and "into next week and, in some cases, much longer," a Hawaii Electric Light Co. spokesman said late Sunday morning.

"Depending on the severity of the damage, it could take even longer" than next week for power to be restored to some, HELCO spokesman Darren Pai said. 

Most of the 8,100 customers without electricity are in the Puna district, although there are some in smaller pockets on the east side of the island, Pai said. At this point, HELCO officials are still trying to determine which areas are most vulnerable to longer-term outages, he said.

Hawaiian Electric Co. crews and equipment from Oahu left Sunday for the Big Island to help restore electricity.

Tropical Storm Iselle’s winds and rain wreaked havoc in the Puna area, causing trees to topple and fly into power lines, breaking lines and poles, and the loss of transmission lines almost caused the entire to lose power, HELCO President Jay Ignacio said, in a statement. More than half of the island’s 35 transmission lines went down, including those that serve Puna Geothermal Venture in lower Puna, he said.

Some lines, such as the one that runs from Papaikou to Kalopa Mauka/Makai, have to be partially rebuilt. The transmission line serving PGV, meanwhile, goes through a forested area near Nanawale Estates and crews are having a difficult time accessing the line due to fallen trees. "That area has at least 19 broken poles and will take a very long time to rebuild, staring with bulldozers to clear a path for trucks and crews," Ignacio said. 

"We understand the frustration of our customers who are still without power and sincerely apologize to them," Ignacio said. "We understand that customers want estimated restoration times so they can plan. Unfortunately, the extent of damage is worse than anything we’ve ever seen here. We’re working on providing more specific, reliable estimates and hope to do so by tomorrow (Monday) morning. Customers without power should expect to remain without it well into next week, if not longer."

HELCO crews restored power to a section of Hawaiian Paradise Park late Saturday afternoon and working on doing the same for other customers.

After focusing on repairing the main transmission lines, crews can now focus on restoring power in individual neighborhoods, Pai said.

Priority wil be on bringing service back to the largest number of customers while trying to keep the grid stable, he said. 

Crews from Hawaiian Electric’s Honolulu staff and Maui Electric Co. have been sent to Hawaii Island, along with vehicles and equipment, Pai said. Along with contracted construction and tree-trimming companies, more than triple the number of HELCO’s regular crews are in the field, he said. All workers, including approved utility contractor workers, should be wearing proper identification and their vehicles clearly marked, he said.

Any Hawaii Island customers with outages who have not reported them should call 969-6666, he said.

Pai reminded Hawaii Island residents that downed power lines are dangerous and that they should not attempt to approach them or move them. 

HELCO’s business officers will reopen for normal business on Monday.

Meanwhile, the American Red Cross is continuing its efforts in lower Puna. 

At  late morning, volunteers were canvassing the Hawaiian Beaches subdivision speaking to residents to try to get an assessment of the storm damage.

On Saturday, the Red Cross set up a shelter to support those affected by the storm in Hilo at Aunty Sally Kaleohano’s Luau House on 799 Piilani Street, on the grounds of the Hilo Civic Center.