Four people are dead, including the gunman, after a shooting incident at a bank in the US city of Cincinnati.

Police chief Eliot Isaac said the shooter opened fire at the loading dock of the Fifth Third Bank building.

He said the gunman then entered the bank's lobby where he exchanged gunfire with police. It is unclear if the gunman shot himself or was killed by officers.

One of the victims died at the scene.

Cincinnati mayor John Cranley said the gunman was "actively shooting innocent victims" and that it was a "horrific" scene.