Shark warning signs came down at Nanakuli Beach Park Saturday evening when no sharks were spotted in the area at about 5:30 p.m.

Three aggressive reef sharks wiere spotted Saturday morning within 10 yards of Nanakuli Beach Park prompting lifeguards to put up warning signs, a city Department of Emergency Services spokeswoman said.

The sharks were spotted around 9:30 a.m. and signs were posted warning swimmers to be careful. Officials suspect the sharks were attracted by a school of fish.

Ocean Safety officials reassessed the situation around 1:30 p.m. and determined that the sharks had not left the area. 

It’s the third time the warning signs have gone up at Nanakuli Beach Park in the last month. There were two shark sightings last month..

Meanwhile, six Portuguese man-o-war stings were reported Saturday at beaches between the Royal Hawaiian Hotel and Kaimana Beach, Ocean Safety officials said. Warning signs were to remain up overnight.