Crews will return to the state's Leiopapa o Kamehameha Building this weekend to repair the damage caused by a gas explosion in a communications room, and hope to reopen the office tower Monday.

The explosion early Thursday was believed to have been caused by a gas leak on Beretania Street.

The leak forced the closure of the street much of Thursday, which set off a major traffic jam.

An estimate of the damage caused by the explosion was not available yesterday because officials were still adding up repair and replacement costs.

The explosion blew out the door of the room and sent air-conditioning equipment flying out of a window.

It also set off the sprinklers, getting communications systems wet.

"It was a pretty big explosion," said Russ Saito, state comptroller.

He said some of the equipment was damaged and will have to be repaired.

In the communications room yesterday, workers had cleared out some filing cabinets that were destroyed and had mopped up water on the floor. Over the weekend, crews will be trying to bring the building's Internet and telephone systems back on line. They will also be repairing the air-conditioning system.

The building, also known as the State Office Tower, has 16 stories and multiple state offices.

The explosion was on the mezzanine level.

Some 300 workers have offices in the building and they were not able to get in Thursday or yesterday.

Yesterday, some workers were allowed to briefly enter the building to get any work materials they needed.

The explosion happened about 12:40 a.m. Thursday.

No one was injured, and the exact cause of the explosion was still under investigation.

Gas Company spokeswoman Stephanie Ackerman could not say yesterday when it would be completed.

Saito said it's believed the explosion occurred when gas from the leak seeped up from the road through conduits into the building. It apparently collected in the communications room to cause the explosion, he said.

Also yesterday, Gas Company crews returned to Beretania Street to work on the faulty pipeline.

They will also be at the site today, and hope to have the work completed by the afternoon.