A worker at a Hershey chocolate factory lost her arm when a machine she was cleaning switched on by accident, officials said.

Erica Domen, 32, was cleaning a batter-sifting machine when the accident occurred early Saturday at the company's Oakdale plant, about 100 miles east of San Francisco, said the state division of the Occupational Safety and Health Administration.

She was working alone on the machine when it caught her hand, removing her arm at the shoulder, police said.

"Her arm got caught in some machinery, and it actually pulled her arm off," Oakdale police Sgt. Keri Ford said. "It wasn't a clean cut-off. They weren't able to replace it."

Domen was in shock but conscious when police arrived a few minutes later, Ford said.

"I have no doubt that her co-workers saved her life," Ford said. "They had some kind of cloth and were applying pressure to the open wound."

Officials at Doctor's Medical Center in Modesto said they could not disclose Domen's condition.

Workplace safety officials were investigating.

The Hershey Co. makes Kisses and other products in Oakdale, according to the company's Web site.