WINDHAM (AP) – A father and son who died from carbon monoxide poisoning were using a generator because their account had been closed by Central Maine Power because of an overdue $900 bill, according to family members.

Stewart Townsend, 35, and his 16-year-old son, Nicholas, died Friday as the generator was running in the basement, police said.

Townsend had been using a kerosene Monitor heater, which needed electricity to start, according to his sister-in-law, Pam Aube of Windham. “You do what you got to do to keep your kid warm,” Aube said.

Family members said Townsend normally kept the basement door open, but it was closed along with all of the windows in the house when firefighters arrived. “Somehow the door got shut,” Aube said. “We’ll never know how.”

Without any ventilation the carbon monoxide levels rose to greater than 950 parts per million, investigators said. Workplace safety rules set a limit of 50 parts per million for exposure during an eight-hour shift.

Aube and family friend Janet Snow said Townsend had tried to work out an arrangement with CMP to get his electricity turned back on, but they said CMP wouldn’t work with him. The home had been without power since before Thanksgiving.

CMP is allowed to cut off electricity in the summer, but the Maine Public Utilities Commission prevents electric and gas utilities from disconnecting customers between Nov. 15 and April 15 for nonpayment because cold weather can be life-threatening.

There’s no indication that Townsend sought assistance from the MPUC, said Derek Davidson, head of the commission’s Consumer Assistance Division.