The man calmly walked into the store on Azusa Avenue in Los Angeles area yesterday and grabbed the handsaws, the West Covina Police Department said.
"He just began sawing away," Cpl Rudy Lopez told The Los Angeles Times. "He was pretty much intent on doing what he did."
"The man cut both arms down to the bone as panicked people called 911 for help. The man was passing out as officers arrived," police said.
The man was taken to nearby hospital, where he was undergoing surgery. His condition was not immediately known.