VANDALIA, Ohio -- Authorities in Vandalia said three people were taken to a local hospital after they began breathing in dangerous levels of carbon monoxide inside a local barber shop.

Investigators said three people became sick after visiting a barber shop on E. National Road in Vandalia.

Firefighters said the carbon monoxide levels were 1500 ppm in the barber shop and even higher in a neighboring doughnut shop.

Medics took the three people to Kettering Medical Center where a hyperbaric chamber is available if it is needed.

Firefighter said the carbon monoxide levels are now back at a safe level, but they continue to ventilate the businesses.

Authorities said the high level of carbon monoxide was caused by a heating system that is shared between the barber shop and the doughnut shop.