Maryland Occupational Safety and Health was investigating the accident Wednesday, Peyton said.
Bobby Colvin, president of Local 658T of the Union of Needletrades, Industrial and Textile Employees, a union at the plant, said employees scheduled to work the next shift after the accident occurred were sent home.
Dr. Edward W. Ditto III, deputy medical examiner for Washington County, said, "She was working in the back part of the machine, got caught under a roller and died instantly."
Ditto said she died primarily from trauma to her upper body.
Colvin said the rollers on the machine Stottlemyer was operating weigh about 2,400 pounds.
The rollers of the machine would have been at about the height of the woman's waist, Peyton said, but no clothing was found caught in the machine.
"We don't know if she slipped, tripped or fell," he said.
The accident was being ruled accidental, Peyton said, and foul play was not suspected.
Colvin said Stottlemyer had worked at the plant for about 15 years and was married to an employee there.
Mervin Stottlemyer, her husband of nearly four years, said he works at the other end of the plant in the maintenance department. He said he was present as workers tried to free his wife from the machine.
"There were a bunch of people doing their best to get her free," Stottlemyer said Wednesday evening. "We just couldn't get her out, not right away."
He said there was a lot of confusion during the incident and hearsay in the hours following it, but no definitive answers as to what happened.
Mervin Stottlemyer said his wife, who had a daughter, Jennifer N. Hyatt, 17, from a previous marriage, was an avid church-goer and musician.
Deanna Stottlemyer played upright bass with Ernie Bradley and Grassy Ridge, a bluegrass/gospel band.
"She was just an easy-going person, fun to be around," he said. "She really liked her music."
Chris Mills, Deanna Stottlemyer's sister, said neither she nor her parents were ready to comment at length Wednesday.
"She was a wonderful person and very talented and very much loved," Mills said. "She's going to be greatly missed."
Plant officials issued a statement that said: "All of us at GST AutoLeather are greatly saddened and emotionally devastated about the apparent accident that has taken the life of one of our workers today."
People have been injured at the plant, but no serious accidents have occurred recently, Colvin said.
"I can believe someone getting injured, but not someone getting killed," he said.
Colvin said he's not sure how old the piece of equipment was that Stottlemyer was operating.
The machines have stop buttons, he said, but he didn't know if the stop button was pushed.
He said he heard from other employees that they heard Stottlemyer scream and by then it was too late.
Williamsport Fire Co. Capt. Robert Horning said fire companies from Maugansville, Clear Spring, Halfway and Williamsport were on the scene. Williamsport and Clear Spring emergency services were also at the scene, he said.
Colvin said the union would take up a collection for Stottlemyer's family.
Staff writer Brian Shappell contributed to this story.