A faulty extension cord was to blame for the early-morning blaze that killed two young boys in their Schwenksville home on Wednesday, according to the Pennsylvania State Police Fire Marshal Unit.

The fire was a tragic accident, the state police said Thursday, and began with the electrical failure of the cord, which was plugged into a space heater in a porch area of the two-story home on the 900 block of Summit Avenue.

It was not known Thursday whether the house had been equipped with working smoke detectors, the state police said.

The home belongs to the family of Bryan Lukens, a Montgomery County deputy sheriff and veteran of the Iraq War. 

The Lukens' sons, Bryan Jr., 11, and Parker, 6, were found dead on the second floor of the three-bedroom home. Their father was treated at the burn unit at Lehigh Valley Hospital and released late Wednesday, the Sheriff's Office said. His wife, Tracy, and their 9-year-old daughter, Soffia, were taken to Pottstown Hospital and released earlier that day, according to the office.

The Lukens family is staying with other family members while grieving and recovering from injuries, the Sheriff's Office said.

A GoFundMe page for the family had raised more than $200,000 as of Thursday afternoon.

Family friend Kyle Boelter remembered the Lukens boys as respectful, happy children who looked out for each other. He said Bryan Jr. "was respectful … [but] liked to have fun" and Parker was "always a ball of energy, always had a smile on his face."