This March 19, 2010 booking photo made available by the Seminole County Sheriff's Office, shows John Robert Neumann Jr., who was arrested for possession of marijuana. Neumann killed several people and then took his own life at an Orlando, Fla., awning factory Monday, June 5, 2017. (Seminole Country Sheriff's Office via AP)

ORLANDO, Fla. (AP) — A recently fired worker from an awning company in Florida followed through with a plan to kill his former colleagues, singling out five and fatally shooting them in the head before taking his own life, authorities said.

John Robert Neumann Jr. shot and killed himself at the sound of approaching sirens Monday. He did not appear to belong to any type of subversive or terrorist organization, Orange County Sheriff Jerry Demings said.

“My experience tells me that this individual made deliberate thought to do what he did today. He had a plan of action,” said the sheriff, who wouldn’t say why Neumann was fired in April.

Demings said Neumann had a “negative relationship” with at least one of his former co-workers in Orlando, and he singled out the former colleagues who were shot.

The shooting began after Neumann slipped through a rear door into the cavernous Fiamma Inc. factory, an area larger than two football fields where awnings are stitched together for recreational vehicles. He paused at least once to reload. Seven other workers were inside at the time but were unharmed.

State and federal law enforcement officers converged on the industrial park shortly after 8 a.m. after a woman ran out and called 911 from a tile business across the street, said Yamaris Gomez, that store’s owner.

“All she kept saying was he was holding a gun and told her to get out,” Gomez said.

That woman had been hired after Neumann was fired in April, so he probably did not recognize her and knew she was not a former co-worker, Deming said.

Deming said investigators were looking through any social media postings for clues. Neumann was honorably discharged from the U.S. Army in 1999 and did not have a concealed weapons permit, the sheriff said.

The dead were identified as Robert Snyder, 69; Brenda Montanez-Crespo, 44; Kevin Clark, 53; Jeffrey Roberts, 57; and Kevin Lawson, 46.

Authorities had confronted Neumann once before at the factory, when he was accused of battering a co-worker in June 2014. But no charges were filed after both men were interviewed, and that co-worker was not among Monday’s victims.