The downtown Miami library reopened Friday, days after a shooting ended with one person in custody.
A Miami-Dade County Library spokeswoman said two men were arguing before Wednesday's shooting at the library on Flagler Street.
Miami-Dade police said Roderick Veazy, 64, opened fire at Carl Cooperstein 63, with whom he had previous issues.
Police said Cooperstein wasn't hit and ran for cover.
The library spokeswoman said others in the library also ran for cover, some hiding behind bookshelves and under desks.
Police said Miami-Dade police Officer Saul Rodriguez, who was working an off-duty detail at the library, shot Veazy.
Veazy was taken to Jackson Memorial Hospital's Ryder Trauma Center and will be taken to jail once he is released from the hospital.
The library was closed on Thursday so library staff could recover from the traumatic experience, the spokeswoman said.
Library patrons who spoke to Local 10 News reporter Madeleine Wright on Friday had mixed reactions about security at the library, some saying that more security is needed and others saying that the library is as safe as it could possibly be.
The Florida Department of Law Enforcement is investigating the shooting.