He will travel to China for talks with Xi Jinping, in what could be the Kremlin chief's first overseas trip of his new presidential term
The shooting took place at Cameo Night Club, the Cincinnati Police Department said on Twitter.
A spokeswoman for the department would not confirm the shooting or provide any details.
At least 15 people were shot at about 1 am, WLWT-TV reported on its website. Several of them had life-threatening injuries, it reported, quoting Assistant Police Chief Paul Neudigate.
Hundreds of people were in the nightclub at the time of shooting, Neudigate said.