Lifeguards cleared the waters edging Pokai Bay Beach Park in Waianae at about 11 a.m. today after a shark was spotted about 100 yards from the shoreline in an area fronting the Pililaau Army Recreation Center. 

Shayne Enright, spokeswoman for Honolulu Emergency Services Department, said the 6-foot shark was deemed aggressive because it was thrashing in the water.

Lifeguards have informed beachgoers of the sighting and posted shark sighting signs, Enright said in an email statement. Lifeguards will reassess this afternoon.