The state is investigating a chemical spill that killed hundreds of fish in a drainage ditch along the Pearl Harbor bike path in Aiea.

Hawaii News Now reports that people reported seeing and smelling the dead fish last Tuesday, when state Department of Health workers counted more than 500 dead fish. Officials said water samples revealed the presence of a chemical similar to a cleaner or solvent.

They’re looking into whether nearby businesses might have been responsible. One did have an accidental spill last Monday.

Carroll Cox, the president of the environmental group EnviroWatch Inc., said he observed dead bone fish, tilapia, guppies and crabs. He said it was disturbing to be in a beautiful area only to come upon a "wall of smell."

Authorities want to make sure that chemicals don’t drain into Pearl Harbor. Health officials said the Navy owns the ditch and will clean it up.