WAKE COUNTY, N.C. -- Authorities are investigating what caused a house fire that injured three people.           

It started around 12:30 a.m. Monday on Irelan Drive in western Wake County.           

Three men and one woman were inside the home.

Rescuers pulled 67-year-old Karen Lewardowski and her 41-year-old son, Mark, from the flames. The others escaped on their own.

Karen and Mark suffered serious injuries and were taken to the UNC Burn Center.           

Another son, John Lewardowski, was taken to WakeMed.

The father, 70-year-old Stephen Lewardowski, was not transported.