Police said searching would continue this evening until dark and the Police National Dive Squad has been notified.
A Hato Hone St John spokesperson said they responded to the scene with one ambulance, a rapid response unit, and one operations manager.
St John referred all other questions to police.
Last year, Coroner Robin Kay released findings into two double drownings at Ahimate Reserve in five days – highlighting the dangers of swimming in rivers when the current is strong.
On December 29, 2021, 11-year-old Blae Ler Paw and 29-year-old Mu Mu drowned in the Manawatū River in Palmerston North.
Just five days later, on January 2, 2022, Toetu Tonisitino, 39, and Aukusitino Ioane, 25, died at the same spot.
The four drowned at Ahimate Reserve. Ahimate loosely translates as calm death.
River guardians Rangitāne o Manawatū placed a rāhui on the river on December 29, but there was no signage advising of this. A rāhui is a Māori customary practice where entry to an area is prohibited to allow it to heal after the discovery of a body.
Kay said officials had taken steps to increase safety in the area following the two double drownings.