Marine units searched the swift-flowing Boise River on Monday after receiving a report of a missing kayaker, Boise Fire Department spokesperson Lynsey Amundson told the Idaho Statesman.

The Boise Police Department was also on the scene, Amundson said, and was monitoring from bridges and elsewhere.

At around 2:45 p.m., Boise fire and police units responded to a report of a missing adult male kayaker on the Boise River, according to a news release. By 4:15 p.m., a possible rescue transitioned into a recovery effort after nine units, including the Boise River rescue boat, were unable to locate the man. Boise police assisted the search with drones, the release said.

Witness reports indicated that the kayaker put in at Barber Park and was last seen in the middle of the river channel near the E. Parkcenter Bridge. The Boise Fire Dive Team recovered one inflatable kayak on the river, according to the release, and the incident was turned over to the Ada County Sheriff’s Office as a missing-person investigation.

On Friday, the Boise Fire Department posted a “Dangerous River Condition” notice, meaning conditions are “extremely dangerous” for people and pets. Officials recommended that people not recreate in the river, as conditions could be life-threatening.

As river flows increase because of warmer temperatures and spring snowpack runoff, several stretches of the Greenbelt have already closed because of flooding.