Lifeguards posted warning signs at Nänäkuli Beach Park after a shark was sighted yesterday afternoon.

The shark was estimated to be 8 to 10 feet and was confirmed by lifeguards at about 1:45 p.m., said Bryan Cheplic, spokesman for the city Emergency Services Department. Cheplic said the shark was "displaying aggressive behavior" by chasing turtles in the surf spot known as Depots.

Cheplic said lifeguards cleared the water for about a mile in each direction and posted warning signs.