SPOKANE, Wash. -

The Spokane Fire Department launched a marine rescue along the Spokane River at Greene Street Bridge Tuesday morning but didn't find anyone in the water.

A helicopter hovered over the river while fire crews in boats and along the shoreline looked for a man who witnesses spotted in the water.

Witnesses claim that they saw a man bob up and down in the water several times and then went under the surface and never came up again.

Crews searched the river for approximately an hour before calling of the search.