Hawaii island police have opened a missing person investigation after witnesses reported seeing a man pulled under by rapids off “Boiling Pots” at Wailuku River State Park in Hilo.

Police said the swimmer was last seen in waters off “Boiling Pots” Tuesday afternoon.

Officers received a call for a swimmer in distress at about 1:30 p.m. Tuesday. Upon arrival, witnesses reported that the man was immediately pulled under the rapids upon entry, and did not resurface. They then lost sight of him.

Police commenced a search, with help from the Hawaii Fire Department and the state Department of Land and Natural Resources.

An extensive search is ongoing, but the man has not been found.

A witness has tentatively identified the man. Police, however, are withholding the release of any further information until next of kin can be contacted.

Detectives of the Area I Criminal Investigation Section continue to investigate.

The Hawaii Police Department asks anyone who may have information to contact the non-emergency number at 808-935-311. Anonymous tips can be reported to CrimeStoppers at 808-961-8300.