Tulsa Firefighters responded to the Starbucks at 18th and Yale Thursday morning. TFD said a carbon dioxide detector malfunction and sounded in the store.
Carbon dioxide is used for fountain drinks.
Tulsa fire department says several customers were complaining of headaches and not feeling well so the store was cleared. A spokesperson for the fire department said it is possible that the customers thought they might have been exposed to carbon monoxide when they had not.
No customers or employees felt bad enough that they wanted to go to the hospital. There was no sign of anything hazardous in the store, TFD said.