One of the sharks was reported to be almost two metres long and was in the process of eating a large squid.
The sharks were sighted by the Westpac Life Saver helicopter.
The shark alarm was sounded and swimmers left the water after which life savers removed the squid and then chased the sharks out to see. The Hammerheads were frightened back out to sea.
The three beaches re-opened a short while later.