A propane-powered saw operated indoors likely caused a carbon monoxide-related illness that led to the hospitalization of over a half-dozen people at a nearby child daycare center in Kittery on Wednesday, officials said.

No one was badly hurt in the incident, according to the Kittery Fire Department. 

The fire department stated that firefighters and EMS responded to “a call of potential carbon monoxide” at Building Blocks Learning Center at 1 Route 236 at 3:18 p.m. 

“At the time of the incident staff at the child care noticed an odor, and individuals began feeling unwell,” Maine Department of Public Safety spokesperson Shannon Moss said in a statement released Thursday afternoon. “The providers evacuated the children and staff and called the fire department. There was no alarm activation upon the fire department’s arrival.”

At the time, there were 27 children and about 10 staff members in the building, but fire officials said there were no deaths or life-threatening injuries.  

Seven people were transported to local hospitals.

Late Wednesday afternoon, parents appeared to be picking up their children at the center, while ambulances remained standing by.

Officials from the Kittery Fire Department, Kittery Code Enforcement, the Maine Fuel Board and the fire marshal’s office were at scene until after midnight gathering information related to the incident, according to Moss.

Fire marshal’s personnel found no concerns related to the emission of carbon monoxide with the building’s heating system.

The fire marshal’s office said the source was exhaust from a propane-powered concrete saw. The saw was being operated inside a suite in the same building and adjacent to, but not affiliated with, the daycare center.

“That suite was under construction and the concrete saw had been operated throughout the day,” Moss said. “Propane-powered gas saws are not intended to be operated indoors and are often labeled to prevent use in unventilated space.”

Carbon monoxide from the saw’s exhaust may have infiltrated the daycare through an HVAC air intake duct that services multiple portions of the building, or the gas could have traveled above a suspended ceiling removed during construction, Moss said.

The unit that was the source of the carbon monoxide did have a valid local building permit at the time of the incident, according to Moss.

However, the Kittery Fire Department also found that detectors related to the fire alarm system had been covered, Moss said.

Fire marshal’s investigators have interviewed dozens of people and the investigation is ongoing.

“They are also consulting with the fire alarm company to determine whether carbon monoxide detectors were present, as some smoke alarms and combination smoke/CO alarms are similar in appearance depending on the manufacturer,” Moss said.

Officials praised workers at the daycare center.

“It is important to note that daycare providers of the Building Blocks Learning Center recognized a problem and took action,”  State Fire Marshal Shawn Esler said. “They evacuated children and staff to safety and notified the fire department as soon as they recognized something was wrong. Their quick response, the professionalism of the Kittery Fire Department, and the medical expertise of the Portsmouth Regional Hospital helped prevent a tragedy.”

With reporting by Sean Murphy of Spectrum News.

This story was updated at 10:40 a.m. Feb. 14 to state that there was a valid building permit. A previous story based on information from the Maine Department of Public Safety stated that a construction permit had not been obtained.