BOSTON (CBS) – Seven people were hospitalized after a carbon monoxide scare at a Mattapan triple-decker.

It happened Wednesday afternoon on Woolson Street. Two of the victims were small children.

Aisha Bailey was on the third floor and felt sick. But she had no idea she was at risk until the fire department showed up.

“I was a little nauseous. I did vomit and I didn’t know it had anything to do with this until I got to the hospital,” she said.

It all began when the building’s owner Phil Squires called 911. He was worried about a friend sleeping in his first floor apartment.

“I couldn’t wake her up. That was my concern.”

At the hospital they found the woman had elevated levels of carbon monoxide. At the same time,a worker fixing the furnace in the basement also started reporting symptoms.

Fire trucks and ambulances rushed back to the building to check on other residents.

Some had minor symptoms consistent with high CO levels.

“We did not find any carbon monoxide detectors in the building at all. The fire inspectors are going to cite the property owner for not having them,” said Boston Fire Department Spokesman Steve MacDonald.

Squires insists he did have detectors but says there was not enough CO in the building for them to sound.

For neighbors on Woolson Street the flashing lights brought back flashes of a tragedy just two years ago, when four people were murdered on this street.

“When I saw the police, I thought ok. Who got killed now?,” said Aphrodite Washington.

They were relieved to learn the victims of this carbon monoxide emergency will be ok.

“I don’t know what really happened, but everyone in my family is doing fine” said a man named Mohammad who is the father of the two hospitalized children.

By late Wednesday night, all but one of the victims had been released from the hospital and were back in their apartments.

Fire officials believe leaking duct work was the source of the carbon monoxide. They urge everyone to check the batteries in their CO detectors and to have their heating systems checked.