Berlin, NH- Three people were found dead of apparent carbon monoxide poisoning in Berlin on Wednesday night, and officials said that an improperly serviced heating appliance was to blame.

Officials said that the three victims were found by a family member, who went to check on them after one of the victims failed to show up for an appointment. The carbon monoxide levels were so high, investigators said, that the relative was lucky to have not also succumbed.

“The windows were blackened by smoke,” Police Chief Peter Morency said. “The carbon monoxide reading was 10 times what a body can withstand.”

The call came in at about 7:30 p.m., but officials said that the high levels of carbon monoxide prevented them from entering the home for more than four hours. They found three victims inside.

“One in bed, one on the floor in the bedroom and another one appeared as though he was trying to get out of the bedroom,” Morency said.

The victims were described as a 14-year-old boy, his grandfather and his great grandmother. Officials said it appeared that the boy and his grandfather might have tried to rescue the woman and were overcome. Two dogs also died.

“The chimney was plugged with heavy black sooting that froze,” Deputy Fire Marshal John Raymond said.

Raymond said that the source of the carbon monoxide was traced to an oil-fired hot-water boiler in the basement. He said it apparently had not been professional serviced since 1999 and that the grandfather had been doing the maintenance work himself.

“You shouldn’t be working on your own heating appliance,” Raymond said. “You should have a professional come in to make sure that the flue pipes are clean. A heating appliance should be checked yearly, not every two or three years.”

Authorities said the home was not equipped with a carbon monoxide detector, and a smoke detector had its battery removed.

The names of the victims were expected to be released following autopsies on Thursday.