Zach Fritzhand, who works nearby, said he saw victims lying motionless on stretchers.
"This is a horrific incident and we really are grateful to the quick and decisive actions of the officers and fire personnel who responded", said Isaac. As previously announced, two other victims received at UC Medical Center are deceased. Perez had multiple magazines and around 200 rounds of ammunition, Isaac said.
Investigators believe that Perez legally purchased the 9mm semi-automatic pistol, which was recovered on the scene, Isaac said.
No police officers were among the injured, Cincinnati.com reported.
The mayor said the incident "is not normal, and it shouldn't be viewed as normal", adding the the United States is the only industrialized nation with frequent active shooter incidents. "I think there's something deeply sick at work here".
By the Enquirer's count-which defines "mass shooting" by the total number of victims, not the number of people killed-this is the 15th mass shooting in the area since 2013, and also the deadliest.
Mac Miller Dead at 26
He was later arrested for driving under the influence, reports said. "I really wouldn't want just happiness", Miller said. Law enforcement officials told the website that Miller was found dead at his Los Angeles home on Friday around noon.
"It is all too clear that we have to do more in OH to address the gun violence affecting communities across the state", said a statement from the OH chapter of Moms Demand Action for Gun Sense.
The FBI office in Cincinnati said it had agents on the scene to assist.
-This report was updated at 11:38 a.m.
One victim was identified as 64-year-old Richard Newcomer, a superintendent with the Gilbane Building Company, a construction company based in Cincinnati. Hospital officials said two people died upon arrival while another is still in critical condition.
Witnesses described the terrifying scene.
The Enquirer also reports that bystanders said they heard "perhaps as many as 12" gunshots.
"Everybody was in there crying". "We just saw glass and everything flying". Although people tried to get her attention before she entered the building, she was wearing headphones and did not hear them. "I kind of got down on the ground and then all the cops started coming", witness James Walker told CNN affiliate WLWT.
A large part of downtown Cincinnati was cordoned off after the shooting. "Please join me in praying for the victims, praying for our Country and join me in this fight to end senseless gun violence".