"Five people were in the water and in trouble."
Mr Kerr said one of the victims was a 14-year-old boy who was "taking on a lot of water".
It was understood he was swimming with his older brother and got sucked into the rip along with two other young men and a teen girl.
"[These victims] were way down the other end of the beach and it was a pretty dangerous day to be honest, there was lots of rips running up the beach and they just pulled into a feeder current and that pulled them into a rip and they went straight out."
The swimmers were pulled about 40m offshore, he said.
One of the men who required rescuing had paddled out on a boogie board to try and help, but ended up needing to be saved himself.
"We had four lifeguards involved, two on the IRB and then another one, myself and then another two came down to provide extra support with the stretcher and ambulance."
The 14-year-old boy, initially reported by emergency services as being 16 years old, was transported to Thames Hospital by St John in a moderate condition at about 12.45pm.
Auckland-Coromandel Westpac Rescue Helicopter was called to the scene but stood down, said a spokeswoman for the service.
Mr Kerr said that the mass rescue was yet another reminder for people to take care around water -- and to swim between the flags.
"It's so easy just to wander down to the beach and go for a swim, but it is so important to get between the red and yellow flags because that's the safest area the lifeguards have chosen on that particular beach."