The man who murdered six people in the Miami suburb of Hialeah was a solitary person who had left his job at Miami Dade College when he learned of plans to fire him over concerns he might engage in violence.

Police are continuing their investigation into the reasons Pedro Alberto Vargas, 42, last Friday shot six people to death and held two others hostages before being killed by a police SWAT team.

The shooter negotiated with police until the wee hours of Saturday at the building, where police initially found two gunshot victims identified in local media reports as its property managers.

After the talks broke down, the SWAT team burst into one of the building's fifth-story apartments, gunned down the suspect and rescued the two hostages unharmed.

Authorities are beginning to learn more details about the life of this solitary and repressed man, who according to neighbors was a weapons enthusiast and obsessed with his physical conditioning, spending a lot of time in a local gym.

Vargas, who had interactions with prostitutes and lived with his 83-year-old mother, had quit his job as a graphic designer at MDC after learning that he was going to be fired for keeping "inappropriate" files, Miami's El Nuevo Herald newspaper reported Tuesday.

Evidently, the material Vargas was keeping on his computer represented a "serious threat," given that it consisted of written threats and photos that targeted a former supervisor, although MDC declined to offer more details to the newspaper.

Vargas' former direct supervisor at MDC, Elmo Lugo, told El Nuevo Herald that the threatening texts he had received from Vargas included photos of himself that had been altered to show him decapitated and messages in which Vargas said he hoped Lugo died of cancer.

Police said that on Friday Vargas set fire to about $10,000 in cash he had removed from his bank account.

In addition, he tried to destroy and set fire to his laptop computer.

It was the smoke from those fires that alerted a neighbor couple, who came to the Cuban's apartment but were met with gunfire there and killed.

After that, Vargas knocked down the door of another nearby apartment and killed its three occupants.

Police believe that the sixth victim - a man who was standing across the street - died when a stray bullet fired by Vargas during the shootings inside the building struck him. EFE