Mother shoots intruder to protect her newborn baby. 9-11 operator says it's okay.

Do I approve of this. Absolutely! Mother of the year!

A young Oklahoma mother shot and killed an intruder to protect her 3-month-old baby on New Year's Eve, less than a week after the baby's father died of cancer.

Sarah McKinley says that a week earlier a man named Justin Martin dropped by on the day of her husband's funeral, claiming that he was a neighbor who wanted to say hello. The 18-year-old Oklahoma City area woman did not let him into her home that day.

On New Year's Eve Martin returned with another man, Dustin Stewart, and this time was armed with a 12-inch hunting knife. The two soon began trying to break into McKinley's home.

As one of the men was going from door to door outside her home trying to gain entry, McKinley called 911 and grabbed her 12-gauge shotgun.

McKinley told ABC News Oklahoma City affiliate KOCO that she quickly got her 12 gauge, went into her bedroom and got a pistol, put the bottle in the baby's mouth and called 911.

"I've got two guns in my hand -- is it okay to shoot him if he comes in this door?" the young mother asked the 911 dispatcher. "I'm here by myself with my infant baby, can I please get a dispatcher out here immediately?"

The 911 dispatcher confirmed with McKinley that the doors to her home were locked as she asked again if it was okay to shoot the intruder if he were to come through her door.

"I can't tell you that you can do that but you do what you have to do to protect your baby," the dispatcher told her. McKinley was on the phone with 911 for a total of 21 minutes.

When Martin kicked in the door and came after her with the knife, the teen mom shot and killed the 24-year-old. Police are calling the shooting justified.

"You're allowed to shoot an unauthorized person that is in your home. The law provides you the remedy, and sanctions the use of deadly force," Det. Dan Huff of the Blanchard police said.

Stewart soon turned himself in to police.

McKinley said that she was at home alone with her newborn that night because her husband just died of cancer on Christmas Day.

"I wouldn't have done it, but it was my son," McKinley told ABC News Oklahoma City affiliate KOCO. "It's not an easy decision to make, but it was either going to be him or my son. And it wasn't going to be my son. There's nothing more dangerous than a woman with a child."