Fall River police said six children and two adults were taken to St. Ann's Hospital with symptoms of carbon monoxide poisoning.
Those people returned home Friday and talked about having symptoms as early as last night, but not knowing what they were initially.
The carbon monoxide levels were high enough to put mother Sherry Martin to sleep on the first floor, and finally were enough to bring firefighters to the house after alarms went off upstairs.
"Last think I know was knock, knock on the door and it was him, 'you need to get up, the firefighters want us out of the house,'" said Martin.
Neighbors saw everyone on the front porch and said they seemed to be suffering typical symptoms of carbon monoxide exposure.
"The family was outside, they were complaining about migraines. So mom and five kids went to the hospital on the first floor and then second floor, mom and daughter went to the hospital complaining about migraines, feeling nausea," said Carla Arruda, a neighbor.
Firefighters said carbon monoxide levels were high and they found a faulty furnace in the basement. They said the first floor alarms did not work because batteries in them were dead or missing.
"The first floor didn't get the alarm, second floor did. Like I said, with the balloon frame, how much of a response difference, I'm not sure, but it was probably a little bit of a difference," said Neil Furtado of the Fall River Fire Department.
Fire officials said everyone was expected to be okay, but the situation demonstrated the importance of smoke and carbon monoxide detectors and making sure they have good batteries.