Firefighters went to the West Terrace Apartments, a six-unit complex in Teaneck, after a carbon monoxide detector there was activated around 5:40 a.m.
They soon determined that a malfunctioning boiler was causing high levels of carbon monoxide, so they ordered residents to leave their units while the boiler was shut down.
Two residents were taken to a hospital for treatment of undisclosed injuries, while several others declined medical attention at the scene.
Officials say all residents should be able to return to their units by Sunday afternoon.
