HONOLULU -- About 2,000 jellyfish washed up onto Oahu South Shore beaches on Tuesday morning, a city Ocean Safety and Lifeguard Services Division spokesman said.

The box jellyfish washed up on shores from Waikiki Beach to Ala Moana Beach Park, the city said.

Lifeguards posted warning signs at Waikiki Beach and Ala Moana Beach Park.

Lifeguards treated 174 people with stings, mostly in the Waikiki area. Only one man who was taken to the hospital after he was stung because he had trouble breathing, officials said. He was in stable condition.

"Ocean Safety personnel would like to remind beachgoers to heed all warning signs and to please check with them before entering the water today," spokesman Bryan Cheplic said.

Cheplic said that Tuesday should be the peak of the monthly invasion of jellyfish. 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.