BOSTON -- Four people were taken from a Hyde Park home early Monday after apparently succumbing to carbon monoxide poisoning, Boston fire officials said.

Crews were called to a single-family house 71 Warren Ave. in Hyde Park just before 8 a.m. after getting a report of an unconscious person. Four people -- an unconscious boy, two other boys and a woman -- were taken to the hospital for exposure to carbon monoxide.

Homeowner Jen Louisia said a carbon monoxide detector went off the day before and he called 911.

"The fire station come in, they test it, they told me I don't need to worry. They said don't worry about it, change the battery," he said.

Officials said the boiler is the likely culprit. Investigators are trying to determine why fire department meters did not detect elevated levels Sunday night.