MINNEAPOLIS — Andrew Engeldinger’s parents were worried about their son’s growing paranoia. In 2010, they sought help, enrolling in a 12-week class for families of the mentally ill.

For the last 21 months, the family said they reached out in hopes he would seek treatment. It was to no avail, as Engeldinger spurned their attempts at contact.

On Thursday night, they learned he was the gunman in Minnesota’s deadliest workplace shooting. Police say Engeldinger fatally shot five people and injured three at Accent Signage Systems in Minneapolis before turning the gun on himself.

“It’s not unusual when you’re isolating yourself, which we know that he did, that eventually the only people you have left is your family and your co-workers, and often your paranoia translates to them,” Sue Abderholden, a mental health organization executive who is serving as spokeswoman for Engeldinger’s family, said Saturday.

Police say the 36-year-old Engeldinger shot and killed Reuven Rahamim, the founder of Accent Signage Systems; employees Ronald Edberg, Rami Cooks and Jacob Beneke; and Keith Basinski, a UPS driver who made a delivery at the wrong time. Two other employees remained hospitalized, one in critical condition and the other in serious condition.

The officers who responded to what Police Chief Tim Dolan called a “hellish scene” eventually found Engeldinger’s body in the basement. Officers who searched his south Minneapolis home later Thursday found another gun and packaging for 10,000 rounds of ammunition.

Police and company representatives have not yet said why Engeldinger was fired from a job he had held since the late 1990s.

Jim Dow, a sales representative who frequently visited the business, said Saturday that he’d spoken to Accent employees and family members of victims.

He said they told him that in recent months, Engeldinger had been running afoul of managers with confrontational behavior and unexplained absences from work.