HONOLULU -- More than 700 box jellyfish washed onto Oahu's south shore as part of the monthly influx on Tuesday, a city spokesman said.

Workers found 679 jellyfish on Waikiki Beach and 86 on Ala Moana Beach Park, Emergency Services Department spokesman Bryan Cheplic said.

Lifeguards treated 13 people for jellyfish stings in Waikiki and one victim at Ala Moana Beach Park, Cheplic said.

Lifeguards posted jellyfish warning signs along some beaches.

The monthly event happen happens seven to 10 days after a full moon.

Beachgoers are advised to look for posted warnings signs or to check with a lifeguard, especially if they are allergic to jellyfish stings. Anyone who is stung by a jellyfish should flush out the sting with vinegar.

If the sting causes cramping or persistent pain, a person should seek medical attention.