City officials say shark warning signs have been posted at Nanakuli Beach Park in West Oahu after a sighting this morning.

At about 10:42 a.m., Honolulu lifeguards spotted an 8- to 10-foot, non-aggressive shark about 300 yards offshore of Nanakuli Beach Park.

Signs have been posted, and beach and ocean patrons have been warned of the shark sighting. About 20 people were in the water at the time of the sighting and all exited safely, according to officials.