Shark warning signs are posted in the areas of Makaha and Yokohama beaches.
Honolulu Ocean Safety says there was an unconfirmed report of a man who was injured by an apparent shark at Makaha Beach at around 7 p.m. Wednesday.
Emergency Medical Services had no patient to respond to. Lifeguards had also left for the day.
Today a 10-foot shark was spotted about a half-mile off of Yokohama Bay.
Ocean Safety will re-evaluate Friday morning.