Honolulu firefighters extinguished an early morning fire that broke out at the H-Power facility at Campbell Industrial Park.

Ten units with 35 firefighters responded to the fire at 91-174 Hanua St. at about 12:35 a.m. today.

Upon arrival, they observed a large fire inside the facility. Honolulu Fire spokesman Capt. Scot Seguirant said welders were reportedly working on equipment at the time the fire broke out.

Firefighters brought the fire under control at 3:30 a.m. and extinguished it at 4:30 a.m.

Investigators determined the fire was accidentally caused by welding work on equipment.

Seguirant said flames scorched recycled material but did not cause any damage to the building or equipment.