CARLTON, Ore. (AP) — More than a dozen people were exposed to carbon monoxide at pork and beef facility southwest of Portland.

Yamhill County Fire said the Carlton Farms retail and packaging areas were evacuated just after 11:30 a.m. Monday after carbon monoxide spread through the air conditioning system, KATU-TV reported.

In total, authorities said 17 people were treated for carbon monoxide exposure. Eleven of them were transported to a hospital with symptoms including nausea, vomiting and headaches. It appeared no patients were in serious condition, KOIN-TV reported.

McMinnville Fire officials said seven agencies responded to the Carlton Farms plant after reports of a boiler malfunction.

No further information was immediately released.