Porter County Coroner Chuck Harris identified the gunman as Roy L. Ferguson, the Gary (Ind.) Post-Tribune reported. Ferguson is from Texas, but it was not known where in the state, the newspaper said.
Harris said Ferguson had two gunshot wounds to the head and one to the body.
The standoff began at 10:05 a.m. Friday at the Prudential real estate office in Valparaiso, Ind., when a man with a gun entered the building because he believed an employee owed him money, authorities said.
Police and the gunman exchanged gunfire at the entrance to the building and all but three employees fled the building within 10 to 15 minutes.
The gunman struck one employee, who was among the first to get out of the building and was treated and released from a hospital for a minor head injury, police said.
The last two hostages got out of the building between 3 p.m. and 4 p.m.
After police heard gunshots, three SWAT team members forced their way into the building at 4:40 p.m. Friday. Flash grenades were set off and the officers broke in through a first-floor window.
Police declared the standoff over about 10 minutes later.
Police said Ferguson had connections to the area but were still gathering information on his history.