Newly released security footage from inside the lobby showed the gunman firing randomly while carrying a briefcase with hundreds of rounds of ammunition over his shoulder.
Cincinnati City Councilman P.G. Sittenfield tweeted one of the first indications that some people had been killed.
Bank manager Greg Harshfield, who on the 29th floor of the building when the shooting began, said that he heard multiple shots and saw police arrive nearly immediately. Three other victims have passed away from injuries sustained.
Emergency officials rushed four more victims to a local hospital, where two were later pronounced dead. He saw a woman about to enter the bank and people shouted at her, he said, but she had headphones on.
About 4 minutes, 28 seconds passed between when Perez fired his first shot and he was stopped by officers, Isaac said. Isaac said the shooting took place in the building's loading dock and then the lobby.
"There are not additional threats to the public", he said. Police later swarmed an apartment in North Bend, Ohio, a village some 15 miles west of Cincinnati. UC Health spokeswoman Kelly Martin said one victim remained there in critical condition and another was listed as serious. Four officers shot at Perez, killing him, Isaac said.
Video caught on nearby surveillance cameras would also be made public once cops have screened it, Isaac said.
Authorities said the death toll in a gunman's attack on a downtown Cincinnati office building could have been higher.
"These are things we see happening across the country, and we all have to be vigilant and prepared to deal with these situations", Isaac said.
Streets and sidewalks around Fountain Square were closed.
One was a longtime construction worker who was overseeing a project in the building.
Austin, a senior product manager based in Louisville, was on a conference call when she walked through the front revolving doors of Fifth Third Center.
The other two killed are 48-year-old Luis Calderon and 64-year-old Richard Newcomer.
"This is a shock that none of us could have ever expected and we're focused on praying for his family and getting through this", Cotter said.
Fifth Third, which operates 1,200 banking centers across several states, in a statement offered its "thoughts and prayers" for everyone "caught up in this awful event".
Two other people were wounded.
Pruthvi is said to have been working in the bank for the last three years.