HONOLULU -- Hawaiian Electric Co. officials on Thursday told members of the state's Public Utility Commission that workers shut down two power units that contributed to Sunday's power outage on Oahu following the earthquakes.

For more than two hours, HECO officials answered questions about what led to the island-wide power failure and why it took so long to restore electricity.

They told the PUC that the two power units that shut off were done manually and not triggered by computers as HECO initially reported. It was having the two units down, coupled with hydraulic problems with an additional two others, that led to the blackout, they explained.

"All of those senses and those alarms and the severe shaking -- they had a potentially serious situation, and so they tripped the units appropriately in accordance with their training," HECO Senior Vice President Tom Joaquin said.

"So in your mind, when they heard those alarms that was the right thing?" KITV reporter Catherine Cruz asked.

"Absolutely," Joaquin said.

HECO has asked for a confidential meeting with the PUC to talk about security issues.

"There are some things that in the wake of 9/11 we agreed not to discuss. We may or not need the briefing, but there are certain things we have agreed not to disclose as far as details about our system. But at today's, we tried to make open -- put on the record as we possibly could. We didn't hold back. We didn't have a confidential briefing first," HECO Vice President Robbie Alm said.

HECO is scheduled to hold a public meeting at the state Capitol on Monday at 2 p.m. Residents who want to hear first hand what happened and ask questions can attend.