Sgt. John M. Russell, a 44-year-old communications specialist from Sherman, opened fire at the Liberty Combat Stress Center on Camp Liberty at about 2 p.m. Monday, officials said. The center is a clinic where troops could go for help with combat stress or personal issues.
His father, Wilburn Russell, said his son got into a fight with the clinic's staff, apparently over being removed from his position.
"They broke him. They told him, 'That's it, you're out,'" he said. "He thought his life was over. They didn't tell him any different."
An armed soldier escorted his son from the premises.
"I don't know if they placed him under arrest or not, because he was argumentative with them," he said. "They put him in a vehicle with a guy with a gun. They already trained him to kill. John took the gun away from the guy and drove back."
He returned to the clinic with the soldier's weapon in hand and allegedly opened fire.
Russell, who had been undergoing counseling, has been charged with five counts of premeditated murder and one count of aggravated assault.
"Tell all of America, we're really sorry," his father said Tuesday, as he stood outside the two-story home his son purchased less than a year ago.
John Russell was born in Oklahoma City and lived in Plano from 1972 to 1976 before moving to Sherman.
"We thought he was well-rounded, but he was real quiet, and he couldn't articulate, he couldn't resolve his differences verbally, evidentially," Wilburn Russell said.
Russell had had his weapons taken away by his superiors over concerns about his mental state, military officials said.
"Either by his actions or by something he said, there was a concern he should not have a weapon, and so the chain of command confiscated his weapon, which is something that is not done routinely to average soldiers, but it is a routine tool that a commander and chain or command has," said Maj. Gen. David Perkins, a military spokesman.
Russell was on his third tour of Iraq and previously had deployed to Bosnia and Kosovo. He was due to return home in just a few weeks.
Wilburn Russell said he found out about the shootings from his daughter-in-law on Monday.
"We've been praying for the families, because he did an awful lot of harm," he said. "He didn't rationalize. He didn't think this thing through."
Wilburn Russell said his family has been through a lot lately. He said he has recently faced serious medical issues and that his grandson, John Russell's only son, just found out that he has cysts on his liver. But he said he never dreamed this would happen.
"You never know what triggers it," he said. "You just know that they're under a lot of stress, and he didn't know how to handle it."
Wilburn Russell said his son has hurt more people than he ever realized.
"I'm sick. I'm sorry, not just for my son, but everybody involved. It should have never happened. You'd think they'd been smart enough to realize a man can only take so much," he said, breaking down into tears.