A disgruntled former employee returned to an Orlando RV accessory business and fatally shot five people before killing himself, authorities said.

Orange County Sheriff Jerry Demings said the 45-year-old shooter, who had been fired in April, entered the Fiama Inc. building at about 8 a.m. ET and opened fire. A 911 call came in at 8:03 and officers were on the scene two minutes later, Demings said.

Four of the victims, three men and a woman, were found dead at the scene. Another man died a short time later at a hospital. The shooter's body was also found at scene. Seven people in the building survived the rampage and were providing details of the shootings, Demings said.

“He shot five innocent people this morning then turned the gun on himself," Demings said. "We have no indication that this person is a participant in any type of terror organization."

Demings said the shooter had previously been accused of assaulting a co-worker but not charged. The victim in that case was not among the victims Monday, he said.

Otherwise, the man had few prior contacts with police, Demings said.

“It’s a sad day for us once again in Orange County,” Demings said during a news conference about 11 a.m. “Our hearts and prayers go out to the victims.”

Shelley Adams told WFTV that her sister, Sheila McIntyre, called her from inside the building during the shooting. Adams said McIntyre was in a bathroom when she came out and saw someone down on the floor.

“She just kept saying, ‘I’m OK; I’m OK,’” Adams told the TV station. “She just kept saying, ‘My boss is dead; my boss is dead.’”

Shortly after the shooting took place, the sheriff's office tweeted that it was investigating a "multiple fatality" shooting at a business headquarters in Orlando, adding "situation contained."

"Now investigating tragic incident & will soon have accurate information," the department tweeted.

The shooting was being handled locally as workplace violence and had no apparent link to terrorism, an FBI official who was briefed on the matter told USA TODAY. The official requested anonymity because the agency is not leading the investigation.

The shooting took place in the city still healing from the Pulse nightclub massacre almost a year ago. In that case, a lone gunman entered the club and shot 49 people to death and wounded several others before he was fatally shot by police.

Streets in an industrial area of the city where the shooting occurred Monday were closed, and patrol cars, officers and police dogs swarmed the scene.

Gov. Rick Scott issued a statement saying he was briefed by law enforcement "on this tragic incident."

“Over the past year, the Orlando community has been challenged like never before," Scott said. "Ann and I are praying for the families who lost loved ones today. I ask all Floridians to pray for the families impacted by this senseless act of violence."