"The subject in this case has been identified as John Robert Neumann Jr., date of birth May 20, 1972," Orange County Sheriff Jerry Demings told reporters on Monday.
Demings said records indicate Neumann was a veteran of the US Army who was "discharged honorably" in 1999,
The sheriff said the shooter was a former employee at the business and was fired sometime in April of this year.
"There is no indication that he used the knife on any of the victims but shot five innocent people this morning and then turned the gun on himself and killed himself," Demings said, adding that there were seven survivors of the shooting.
"We are trying to understand as much about him as we possibly can," Demings added.
Agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), a US federal law enforcement organization, will assist the investigation into the shooting, the bureau announced.
"Special agents from ATF Orlando Field Offices are on scene at Orlando shooting incident to assist our partners," the organization said in a Twitter message.
The investigation into the incident is ongoing, and eight shooting survivors are currently being questioned.
