( CNN ) -- Three people were killed and a fourth was wounded in a shooting Friday at a lumber company in North Carolina , a county sheriff said . Investigators later found a man witnesses identified as the shooter in his home with a gunshot wound to the head , said Sheriff Dempsey Owens of the Montgomery County Sheriff 's Office . Both the fourth victim and the alleged shooter were in critical condition , Owens said . The shooting happened at the McBride Lumber Co. , about a mile north of Star , North Carolina , about 50 miles south of Greensboro , Owens said . All five individuals worked at the company , Owens noted . Investigators summoned to the business around 6:15 a.m. found four people inside who had been shot . Three were dead . A fourth was flown by helicopter to a hospital at the University of North Carolina at Chapel Hill , the sheriff said . Witnesses identified the shooter as 50-year-old Ronald Dean Davis . Law enforcement officers who went to his home discovered him sitting on a couch with a gunshot wound and a rambling six-page note beside him , Owens said . Owens said there 's a `` possibility '' Davis was being harassed at work , though he stressed that investigators had not yet identified a motive . Davis , also hospitalized at the university facility , `` knew who he went after , '' Owens said . CNN 's Mark Bixler and Alan Silverleib contributed to this report .
NEW : Fourth victim and alleged shooter remain in critical condition . Four people were shot at a lumber county in North Carolina . Three were killed while a fourth was hospitalized . Police later found the suspect at home with a gunshot wound to the head .