Friday, power to the building was finally restored, but nearly 300-employees who work there, are still asked to stay home.
The blast happened on the mezzanine level of the building. Officials say if it was any other time of the day when the area is usually packed with people, someone could have easily died.
Downtown drivers were in traffic deadlock for hours as gas company crews worked to repair a gas line below busy South Beretania Street.
"We just turned power back onto this building," said State Comptroller Russell Saito.
An explosion happened in an unmanned communications room. But minutes before, fire crews were checking out a gas smell outside the building. But, there aren't any gas lines here.
"Their concern wasn't so much they detected it here, they wanted to find the source," said Saito.
"While they were investigating an explosion occurred," said Honolulu Fire Department Captain Terry Seelig.
The blast's impact made an ac-unit a wall accessory. Aside from extensive electrical repairs, there are no structural damage or injuries.
"They go down under the ground and go across the street," said Saito.
The state can only guess how the gas got into the building.
"There was a leak in the gas line on Beretania. The gas somehow got into these ducts and conduits," said Saito.
But that isn't known for sure yet. As the clean up continues, officials work to come up with a more concrete conclusion.