A man armed with a handgun and a knife shot and killed five employees at his former workplace in Orlando, Fla., Monday morning before turning the gun on himself, authorities said.

The 45-year-old “disgruntled” ex-employee walked into the warehouse headquarters of the RV awning company, Fiamma Inc., and opened fire on workers inside, Orange County Sheriff Jerry Demings said at a press conference.

The 8:03 a.m. shooting left three men and one woman dead at the scene. A fourth man died at the Orlando Regional Medical Center as a result of his injuries, authorities said.

The gunman, whose identity was not immediately released, killed himself after the carnage on North Forsyth Road near Hanging Moss Road in Orange County.

He had been fired from Fiamma Inc. in April, said Demings, noting that the shooter had also been involved in another incident at the business in June 2014 in which he allegedly “battered” a co-worker.

No charges ever resulted from that incident and that co-worker did not appear to be one of the victims who were slain, Demmings said.

“There is no indication that he used a knife on any of the victims,” said Demings, adding that seven people survived the horrifying incident and were being interviewed.

The shooter has a criminal history involving “minor” offenses, which include possession of marijuana, DUI and a misdemeanor battery charge, said Demings.

A woman, Shelley Adams, told reporters that her sister, Sheila McIntrye, was in the bathroom of Fiamma – where McIntrye works – when the shots rang out.

“She just heard a bang and when she came out she saw one person on the floor,” said Adams, who talked to her sister on the phone immediately after the shooting.

“She just kept saying, ‘I’m OK. My boss is dead! My boss is dead!’ very, very upset,” Adams said.

“We’re just going to embrace her and not leave her alone and just be there as a family,” said Adams. “It’s unbelievable that it could happen in a small business.”

The Orange County Sheriff’s Office was on the scene within two minutes of receiving the 911 call of a report of an active shooter.

Officials from the FBI Joint Terrorism Task Force also responded to the scene even though the incident was deemed to be “workplace violence.”

Orange County Mayor Teresa Jacobs said at the press conference: “Unfortunately, we’ve seen this play itself out in our community and other communities across the nation. It is incumbent upon all of us not to be become complacent or callous to each of these situations.”

Florida Gov. Rick Scott called the incident a “senseless act of violence” as he expressed his prayers for the victims’ families.

“Over the past year, the Orlando community has been challenged like never before…I ask all Floridians to pray for the families impacted by this senseless act of violence,” said Scott.

Almost a year ago, Orlando was the site of the nation’s worst terror attack since 9/11. A gunman killed 49 people at the Pulse nightclub on June 12, 2016.