BELLINGHAM, Wash. (AP) — Sixteen people at a seafood business in Bellingham were sent to hospitals to be treated for carbon monoxide poisoning Tuesday, officials said.

Bellingham Fire Chief Bill Boyd said the people were overcome by fumes at the Homeport Seafoods cold storage business. The fire department responded to a call at 8 a.m. about a person passing out. When firefighters arrived they found everyone conscious, but people showing symptoms of carbon monoxide poisoning.

Investigators suspect warehouse doors — closed due to freezing temperatures — trapped carbon monoxide emissions from forklifts, Boyd said.

The fire department transported the 16 to St. Joseph Hospital in Bellingham, and four were later transferred to Virginia Mason Medical Center in Seattle, where they could be treated in a hyperbaric chamber, which increases oxygen pressure in body tissues and the amount of oxygen blood can transport. Boyd said others may have gone to hospitals on their own.

A manager from Homeport Seafoods declined to comment.

Bellingham is about 88 miles north of Seattle. A cold front has brought below-freezing temperatures to most of Washington state.

Tony Gerbino, head of hyperbaric care at Virginia Mason, said people should be careful about running generators inside or close to windows of their homes. Symptoms of carbon monoxide poisoning include headaches, nausea and vomiting.

In late 2006, eight deaths were blamed on carbon monoxide poisoning in the Seattle area after people tried to keep warm by lighting barbecues inside their homes during a cold spell.