Jacksonville Sheriff's Office spokeswoman Melissa Bujeda said an unknown number of hostages were inside the Community First Credit Union.
An initial 911 call reporting a bank robbery came in at 9:06 am. A short time later, another call indicated that someone may have been shot, but the sheriff's office has been unable to confirm that, Bujeda said.
Police negotiators also were present, the spokeswoman added.
Streets surrounding the bank were blocked by police, and Bujeda urged patience from business people unable to get to work.
"Situations like these sometimes can be short and sometimes can be long," she said.
Bujeda urged local TV reporters not to show their positions around the bank because that could pose "a danger to officers as well as the individuals in the bank." The bank is located in a northwest Jacksonville commercial district surrounded by a storage facility and a dollar store.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)