Tonight we have a new video tape which shows how a police officer with nerves of steel saved a life. It happened in a walmart, in a split second a stranger seized a child and rob nelson takes tus... See More
Tonight we have a new video tape which shows how a police officer with nerves of steel saved a life. It happened in a walmart, in a split second a stranger seized a child and rob nelson takes tus through what police did and we want you to know some of this is intense. Reporter: A mother and her two young daughters shopping at an oklahoma walmart. Little did they know that man right there was about to strike. As the mother turns toward a grocery shelf, 37-year-old sammy wallace snatch is the girl from the shopping cart. Here it is again the toddler in the stranger's arms. 9/11? We need police. Reporter: The mother con front him and another shopper blocks him in. Police arrive beginning 34 minutes of a rescue operation. He has a violent arrest record and a history of mental illness but it doesn't work. Every time we felt like we could use the cues, talk to him about his family, job, his interest, he would become erratic. Reporter: The team moves in. A police officer to either side of the suspect. It's called triangulation. We can try to get a got shot if we need to. Reporter: Next they offer him a chair, a controlled target. Suddenly the suspect starts counting down from 60 seconds. Police fear they are out of time. His eyes got wide. He moved a knife from her stomach area up to her throat. Reporter: Watch the one offer krauch down as the second officer just out of sight begins to speak distracting the suspect who tufrns his head to the left just for a second but it's the opening the captain needed, moving forward, shooting the suspect at point blank range, pulling the toddler to safety. The captain's actions were heroic and he waited until the very late moment. Reporter: Quick thinking by police saving a lucky little girl who tonight is back with her grateful mother. Rob nelson, abc news, new york.
This transcript has been automatically generated and may not be 100% accurate.