Allentown, PA – A 9-year-old Allentown boy was overcome by carbon monoxide and three other people were sickened Friday evening, hours after the heat was turned on in their home for the first time this season, officials said.

The boy was taken by Allentown EMS to the hospital after family members at 126 Donald St. noticed an odd odor and the boy passed out about 6:45 p.m., city fire Capt. John Christopher said.

“We had levels of carbon monoxide of 500 parts per million,” Christopher said. “That’s very significant. That can be lethal.

A man, woman and 10-month-old baby from the same house went to the hospital separately in a private car. The man had been unconscious briefly, according to emergency radio reports.

UGI turned off the home’s gas service until repairs are made. Christopher said officials are not sure what went wrong with the heating system.

The residents turned the heat on about 3 p.m. Friday. They didn’t notice a problem until after 6:30 p.m.

A woman who lives in the attached house next door came home to see firetrucks and other officials at the scene. When she noticed that some of the odd smell had drifted into her upper rooms, firefighters set up fans for ventilation.

One resident of 126 Donald St. said he was downstairs and was not affected by the gas. He said the others were upstairs and they seemed to notice the problem all at once.

“Everyone came down saying they smelled a crazy smell,” he said. “We evacuated to the porch. It just seemed something wasn’t right with one of the kids.”

He said the 9-year-old boy seemed to drop asleep on the front porch. Firefighters said they believe all involved will be fine, but there was no official information on the conditions of the four residents.