Power was restored in downtown Honolulu at about 8 p.m. Thursday after a nine-hour outage left much of the area in the dark most of the day.

The outage affected 900 customer accounts — many of which were “master-metered office buildings and condominiums that have hundreds of tenants” — according to Hawaiian Electric. The affected area from Chinatown to the Capitol District included office buildings, condominiums, the state Capitol, the U.S. post office, state courts and the federal building.

Traffic signals in the downtown-Chinatown district — between River and Alakea streets, and between Nimitz Highway and Beretania Street — also were without power, with Honolulu Police Department officers directing traffic at many intersections.

“The incident resulted from a sequence of events that started at approximately 9:30 p.m. Wednesday, when an outage affected the area between Bishop and Mililani streets downtown,” Hawaiian Electric officials said in a news release. “That outage damaged an underground cable that feeds power into the downtown area.

“Subsequently, shortly after 10 a.m. Thursday, equipment at the Iwilei substation experienced an overload of power. This caused the broader outage.”

Repair crews were on-site in the area beginning at around 10 a.m. as they worked to “repair cables in underground vaults below the streets and on damaged equipment at Iwilei substation,” the release read.

Most of the downtown Honolulu area is served by a network of underground cables that run below the streets, according to the company. This network was originally built in the 1960s and 1970s, Hawaiian Electric said, and while sections have been updated and maintained over the dec­ades, much of the original cable remains in service.

The state Department of Accounting and General Services closed to the public state offices in the buildings affected by the outage until further notice. Affected buildings included the Capitol, Judiciary, Kalanimoku, Kamamalu, Keoneana, State Office Tower, No. 1 Capitol and Kekaunaoha buildings, DAGS said.

“We know this was an extremely challenging day for our customers in the downtown area and Chinatown, especially businesses and government offices,” Hawaiian Electric spokesperson Darren Pai said. “We thank them for their patience and offer our sincere apologies for the disruption.”

The company said power to downtown circuits began coming on at about 7:20 p.m., about nine hours after the outage began for most customers.

Hawaiian Electric said because the outage affected so many underground systems, repair crews and technicians would remain on standby overnight and closely monitor the downtown network and the Iwilei substation, where equipment was damaged by the event. The company said customers should monitor Hawaiian Electric’s social media channels and local news media for any changes in status of the downtown grid, especially before heading to work today.

Customers can report power outages by calling 855-304-1212 or visiting Hawaiian Electric’s website Opens in a new tab at hwnelec.co/MTLa50Siy5a Opens in a new tab.