Mike and Joanne Penza and Mike's mother, Netta, turned on the heat in their home, then became sick. Family said Mike called his brother when he had symptoms and someone came over to check on them, calling 911 right away.
"It's scary because you can't smell it or see it," said Jason Nali, their nephew, who transported their four dogs for treatment, as well. "You hear all the time people pass away in their sleep from this."
Nali said they were all experiencing different symptoms, including chest pains and being delirious and unable to stand.
The Plymouth Fire Department responded right away and determined carbon monoxide was the issue, and that the heating system was the source. They said an expert needed to come in now to see exactly what went wrong within the heating systems.
Nali said their alarm was going off, but it might have gone off too late.
"The alarm did go off, but at that point, everyone was confused and disoriented," said Nali.
Their neighbor of 33 years, Steve Madden, said you can never be too careful. He said he checks his carbon monoxide detectors regularly.
"Anytime you see something like that, you always worry it could be something fatal or something bad has happened," said Madden.
Nali is relieved 911 was called right away.
"This could have been a very different situation," said Nali.
The family and their dogs will be treated overnight. A family member said Mike's CO levels are still very high and not coming down as fast as they would like. He will be put into a hyperbaric chamber in hopes that will change, but he might need to be transferred to a Boston-area hospital. The carbon monoxide levels could cause some heart damage, according to medical officials.