A Pennsylvania father and his two sons perished after their house caught fire, likely due to a Christmas tree and electrical issues, officials say

• A father and two sons died in a house fire Saturday, likely due to a dry Christmas tree or electrical issues.
• Two family dogs also died in the fire. The mother and eldest son survived with minor burn wounds.

A father and two sons in Pennsylvania died on Christmas Day after their house caught on fire.

"The area of origin was a Christmas tree, so we're not sure if it's because of electric or a dried up old Christmas tree," Fire Marshal Doug Wilhelm in Quakertown, Pennsylvania told CNN.

The family had been sleeping when the fire broke out, Wilhelm said. Police and firefighters struggled to enter the home when they first arrived at the scene because the fire quickly spread and obstructed the entrance.

"It was too dangerous to get inside on the front side of the building with the fire," Wilhelm told CNN. "The front door and front window were blocked, fire was advancing to the entire home at that point. It was very difficult for firefighters to make a safe entry. It took a while."

When they were finally able to find a way in, firefighters found three dead bodies. Eric King, 41, and his two school-aged sons died on the second floor, Wilhelm told CNN. Two family dogs also died, according to Wilhelm. The two sons, one a fifth-grader and the other a third-grader, attended Richland Elementary School in the Quakertown Community School District.

"It is with unbearable sorrow that we share with you this Christmas morning the tragic news that the King family, in a house fire early today, lost their father and two Richland Elementary School students," the Quakertown Community School District said in a Facebook post Saturday.

The mother and the family's third and oldest child, Brady, survived with minor burn injuries.

A GoFundMe started in the wake of the tragedy has surpassed its $20,000 goal, nearly reaching $400,000 as of Sunday morning.

The entire home had been destroyed by the fire, the GoFundMe says. King and his wife, Kristin, were high school sweethearts, and all three boys were active in the community and at school.

The parents "were always smiling and full of positive spirits, you just couldn't help but to love them," the crowdfunding account says. "The three boys, Eric and Kristin were all a huge part of the Quakertown Youth Baseball Association and spent their days and nights at the baseball fields."

Later this week, the coroner's office will conduct an autopsy on the bodies of the father and two sons.