More than a quarter of Hawaii Electric Light Co. customers lost power Thursday evening after two power plants tripped offline.
The utility said 24,000 customers, or 28 percent of the total, were affected.
Rhea Lee-Moku, HELCO spokeswoman, said the cause remained under investigation.
Affected plants were Hill Plant in Hilo and the Keahole Plant. Load shedding was done automatically as alternate generation was started.
Most customers had their power restored within 12 minutes, while power to remaining customers was restored by 8:24 p.m.
“We sincerely apologize for the power interruption and thank the community for their patience and understanding,” said HELCO spokeswoman Kristen Okinaka.
She said the cause was not lack of sufficient generation.