It took two hours last night for firefighters to extinguish a Hawaiian Electric Co. mobile generator fire at Honolulu Harbor's Pier 31.

The fire started at 6:30 p.m. and was extinguished at 8:30 p.m., said Honolulu Fire Department Capt. Terry Seelig.

Because the generator unit is housed in a 30-foot-long shipping-type container, firefighters had to air out the container and deal with smoldering wiring to put out the fire, Seelig said.

Thirty-five firefighters from six companies were dispatched to the scene.

HECO spokesman Jan Loose said the fire did not cause any power failures.

The generator involved is one of three "distributed generator units" in the area, said Loose. The mobile generators are used to provide extra power when needed, he said.

The cause of the fire is under investigation and damage estimates were not immediately available, Seelig said.

"It does not appear to be suspicious," he said of the fire's cause.