CLAREMORE, Oklahoma - Six people - including three firefighters - were taken to the hospital after a CO2 leak at Claremore's Daylight Donuts on Will Rogers Boulevard.

Authorities closed West Will Rogers Boulevard from JM Davis to Chambers temporarily due to the emergency response Friday.

Claremore Fire Battalion Chief Marty Osborne said they were called to the restaurant on a report of a man down. When they went to the business, they found one man unconscious outside and two more victims inside.

Those people were members of a cleaning crew, Osborne said. All were suffering from respiratory issues.

Three of the firefighters who responded were also taken to the hospital to be treated.

Although carbon dioxide is in the atmosphere, it can also be dangerous in high concentrations. Fire crews eventually discovered the issue was a leaking CO2 tank hooked to a soda machine inside the donut shop, the battalion chief said.

The three original victims are still being treated at Claremore hospital. The firefighters have been relieved from duty for the night, Osborne said.