(CNN) -- A man shot four men with whom he had worked -- two of them fatally -- in northern Florida on Saturday before shooting and killing himself, the Union County sheriff said.
Sheriff Jerry Whitehead told CNN affiliate WJXT that the Lake Butler "community is in shock," after 72-year-old Hubert Allen Jr. allegedly went on a shooting spree, killing his longtime boss, Marvin Pritchett, 80, and a former co-worker Rolando Gonzalez-Delgado, 28.
Two other men were shot and wounded.
Whitehead said he knew all of the individuals and is Pritchett's nephew.
Lake Butler, where most of the shootings took place, is a small community of fewer than 2,000 residents.
Whitehead said Pritchett was a "self-made millionaire" and "just a great guy, with a great family."
Pritchett's death will have a "terrible impact on the community," Whitehead said.
Whitehead knew Allen for 40 years, and said he'd just talked to him just last week.
Allen was the step-grandfather of Buffalo Bills running back C.J. Spiller, the sheriff said.
A law enforcement authority with detailed knowledge of the case said the gunman had an argument with Pritchett earlier in the week, The same source clarified an earlier report, saying the argument happened Monday and that the gunman was retired from the company, though he was still involved in some capacity and still interacted with its owner.
Whitehead said he couldn't confirm any details related to a motive, but that his department was investigating.
The Union County Sheriff's Office said Allen went to a Lake Butler farm owned by Pritchett, where he fatally shot Gonzalez-Delgado.
A short distance away, Allen shot and killed Pritchett, authorities said.
From there, police said Allen confronted another former colleague driving a farm tractor. The men exchanged words before Allen fired a shot at 66-year-old Lewis "Buddy" Mabrey Jr., striking him in the left arm and side.
Mabrey was rushed to the hospital, where he was expected to undergo surgery for a broken arm and other injuries. He was in good condition.
Allen traveled to Pritchett Trucking Inc. and shot a third co-worker, 44-year old David Griffis, in the stomach, officials said.
Griffis was taken to the hospital for immediate surgery; he was in critical condition.
The suspect then fled the scene to his home, where he shot and killed himself, officials said.
Police say they believe Allen acted alone in these shootings, but they continue to investigate the "heinous crimes."
A statement posted Saturday evening on the company's website said Pritchett Trucking was shocked and mourning the loss of its founder and the employees.
"Words cannot express the pain and sorrow felt by so many, yet we are comforted by the memories of those lost."
According to the site, Marvin H. Pritchett founded Pritchett Trucking Inc. in 1980. The company employs "well over 400 people and is apportioned in all 48 states and Canada."
HLN's Josey Crews contributed to this story.