A substitute music teacher has been arrested after allegedly whacking a 10-year-old student on the head with a viola bow after telling the class they were "the worst players I've ever heard."

Newspaper and television reports said the trouble began when Carla Shinners, 63, a teacher for more than 30 years in the district, was interrupted by a call on her own cell phone. She allegedly began swearing Feb. 12 at the Creekside Elementary School, where she had earned the nickname "Mrs. Grumpy Lady."

Principal Karen Daly said parents and students complained.

The 10-year-old said Shinners also pulled her hair.

Shinners allegedly said the students complained because she was white and they are Hispanic. There was no phone number listed for her in Boulder. It wasn't clear if she had retained an attorney.

Briggs Gamblin, a spokesman for the school district, confirmed in a telephone interview Thursday night that she had been fired.

Shinners could face a charge of child abuse resulting in injury. She is free on $1,000 bond.