Honolulu fire investigators determined a fire at the Hawaiian Waste Systems baling facility began by spontaneous combustion and caused $1.5 million in damages.

The fire started in a pile of garbage on the makai side of the warehouse and also damaged expensive equipment, including a shredder and a bailer, said Honolulu fire Capt. Terry Seelig. Damage to the equipment alone was about $1 million.

The two-alarm fire at 91-236 Oihana St. started about 1:30 a.m. Thursday and was brought under control about 4 a.m.

"The rubbish pile heated up and started to smolder and erupted into flame eventually," Seelig said. 

Company workers used an excavator to pull piles of trash from the warehouse for firefighters to douse. The fire was extinguished late Thursday evening.