GLENDALE, Wis. (CBS 58) -- North Shore Fire and Rescue crews are currently evaluating and treating multiple patients after elevated levels of carbon monoxide were discovered inside a business.

Crews responded to the Boston Market, located at 5470 N. Port Washington Road, around 4 p.m. on Sunday.

We Energies is currently investigating the source of the carbon monoxide.

North Shore Fire and Rescue says the restaurant has about 10 different ovens and so it's unclear what appliance it is coming from.

Stay with CBS 58 News for more information on this developing story.