Sixteen people were hospitalized after inhaling a noxious gas at a food-processing factory in Yokohama, officials with the municipal fire department said.

The incident occurred shortly after 10 a.m. Wednesday at a Foods System factory in Isogo Ward when chemicals were being mixed to clean a machine used to slice frozen tuna.

Hydrochloric acid and sodium hypochlorite are believed to be the main chemicals involved, and one of the victims is seriously ill, the police said.

"It smelled very nasty and I saw some people crouching down on the ground," a male factory employee said.