SAN FRANCISCO (AP) — Looks may not kill, but they can get you fired.

That's what a Northern California yoga instructor found after leading sessions at Facebook Inc.'s Menlo Park campus.

The instructor, Alice Van Ness, said she got fired after she glared at a Facebook employee who texted during a class in June.

"The whole point for most people going to yoga is that it's disconnecting from the outside world," said Van Ness, a 35-year-old San Carlos resident who has taught yoga for six years. "If you are bringing your phone into class, why are you even there?"

Van Ness told the Facebook class to turn their phones off after seeing a female employee with a cellphone out. Later, while demonstrating a difficult pose, she caught the same worker typing on her phone. Van Ness said she stayed silent, but shot the woman a disapproving look. The employee stepped out before returning to the class, Van Ness said.

According to a termination letter from Plus One Health Management that was provided to The Associated Press by Van Ness, she was warned prior to the class that she could not enforce a cellphone ban.

David Milani, a representative of Plus One Health Management, declined to comment specifically on Van Ness' case. But he said company instructors who teach at some companies including Facebook are required to allow fitness members to pick up their phones during class.

Van Ness thought it would blow over, until she was fired two weeks later. The Facebook employee was embarrassed and shocked by the "confrontation" with the instructor, the termination letter indicated. The company feared making clients unhappy, Van Ness said.

"We are in the business of providing great customer service. Unless a client requires us to specifically say 'no' to something, we prefer to say 'yes' whenever possible," an official wrote in the termination letter.

Facebook, in a statement, declined to comment on Van Ness' case, saying it's against their policy to comment on decisions made by outside vendors.

Van Ness said losing the job meant losing a third of her monthly income. But since her story went public, she said she landed a new job - where she's keeping the no cellphone rule.