AURORA, Colo. (AP) _ A woman saved the lives of her two children by breaking into a bedroom engulfed in flames and throwing them out a window to safety, authorities said.

''If it wasn't for the mother entering that bedroom, we would have undoubtedly had two dead children,'' said Fire Lt. Marty La Russo.

Samantha Engelhardt, 23, was awakened from a nap in her suburban Denver home Sunday afternoon by the screams of her 3-year-old son, Jamie, and 18- month-old daughter, Kyra.

After pushing down the bedroom door, which was in flames, she threw a chair through the first-floor window and tossed the children out. Neighbors pulled them away to safety, La Russo said.

Engelhardt couldn't escape through the window because it was too high, so she ran back through the burning apartment and out the door.

The fire was started with matches or a lighter, but investigators don't know who did it, La Russo said.

Engelhardt was in serious condition Monday at Denver's University Hospital with burns. Jamie was in fair condition and Kyra in good condition at Children's Hospital in Denver.