PORTLAND (AP) – A health care facility in Portland that was evacuated following employee complaints of nausea and lightheadedness has reopened.

Officials told the Portland Press Herald that some of the 14 people who became sick Wednesday at Martin’s Point Health Center were suffering from carbon monoxide poisoning linked to a malfunction in the building’s furnace.

Nine people were transported to the emergency room at Maine Medical Center and five were treated at the scene. Martin’s Point spokeswoman Amy Landry said everyone seems to be doing OK.

Firefighters detected no abnormal levels of carbon monoxide in the building and said it was safe to re-enter.

About 100 people work at the clinic. No patients were affected by the fumes.