PORTLAND – Eleven seafood company workers are recovering after being taken to Portland hospitals on Monday for carbon monoxide poisoning.

According to officials, 14 workers were busy inside the crab-picking room when people began complaining of dizziness, nausea and burning of the eyes. After a few minutes workers began helping each other to exits; firefighters said one woman had to be carried out by co-workers.

Rescue workers from Portland and South Portland arrived around 11 a.m. and found all employees had made it outside safely.

Eleven employees were taken to the hospital after complaining of nausea, headaches and other symptoms of carbon monoxide poisoning.

The workers were taken to Maine Medical Center and Mercy Hospital. Two of the patients were transferred to St. Mary’s Hospital and put in a special chamber to reduce carbon monoxide levels.

Fire department investigators and an inspector from the U.S. Occupational Health and Safety Administration are investigating.

Portland Deputy Fire Chief Michael Shutts said investigators are examining several causes, including a propane-fueled heater and the company’s gas-fueled crabmeat cooker.

Most of the workers were Cambodian. Portland’s waterfront provides many jobs to immigrants from Asia and Latin America willing to work hard for long hours.

Pirun Sen, a spokesman for the local Cambodian community and home-school coordinator for Portland schools, said some Cambodian immigrants take jobs with seafood processors in Portland because the work is similar to what they did back home.

Carbon monoxide is a colorless, odorless gas that is produced when burning fossil fuels such as gas, oil, wood and charcoal. The U.S. Consumer Products Safety Commission estimates as many as 200 Americans die each year from CO poisoning.

Symptoms of CO poisoning – headache, fatigue, nausea, and shortness of breath – often mirror those of the flu or common cold. Fresh air is the best treatment for CO exposure.

Ted Fitzgerald, spokesman for the OSHA office in Boston, said a full report of the investigation would be available within two weeks.

OSHA sets permissible exposure limits for carbon monoxide at 50 parts per million, for no more than an eight-hour period. When firefighters arrived at Nancy’s Shellfish, they recorded levels of 280 parts per million.