Eric Peterson heard a bang on his door in his quiet Nashville neighborhood and opened it to a woman covered in blood. She pleaded with him to go rescue her children whom she had left a few doors down to go get help after a woman stabbed her with a kitchen knife. Peterson tried, but by the time he got to the home a few doors down, the baby was gone. Authorities are searching for the baby boy and the woman his mother says was posing as an immigration agent and snatched him from her home. Maria Gurrolla told reporters she had never seen the woman before she showed up at her door Tuesday evening. She said the woman got a knife from the home and stabbed her several times. "I need my baby back," the 30-year-old mother said Wednesday through an interpreter outside Vanderbilt University Medical Center. Gurrolla said she did not see the woman take the baby because she ran to Peterson's home. He told The Associated Press she was "covered from her head to her toe with blood" with gashes on her neck and upper chest. She asked him to save her children from the "lady in the kitchen" who had a butcher knife. He went to the home a few doors down and saw a woman speeding away from the home. He brought Gurrolla's 3-year-old daughter back safely to his house, but found no baby, he said. Gurrolla, who had a long scratch on her face, said the woman, whom she described as a robust white American, did not say anything about wanting to take the baby, who was on the sofa. "She said she was an immigration officer and she was there to arrest her," said Gurrolla's cousin, serving as interpreter. It was not clear if Gurrolla was an immigrant, but police said she has lived in Nashville for at least 10 years. The cousin said the family did not want to discuss her legal status. Police issued an Amber Alert with a picture and description of a 30-year-old woman. They questioned a woman matching the description in Buffalo, N.Y., but determined she wasn't involved. Dr. William Dutton said Gurrolla had a penetrating chest wound and her lung had collapsed. He said she also had deep stab wounds to her neck, but was in stable condition. He said she still has physical signs that she gave birth recently. He described the birth as complicated but declined to elaborate. A blue yard sign outside Gurrolla's home in the community of mostly single-family brick houses in south Nashville announces, "IT'S A BOY!" Police spokeswoman Kristin Mumford said she doesn't know whether Gurrolla was targeted because of the sign. Peterson said as he was making his way to Gurrolla's house, a woman with a ponytail was behind the wheel of a gray 2-door Honda that sped away from the home. As he approached Gurrolla's yard, a young girl in a diaper walked from around the back of the house. He left her with Gurrolla and the woman he lives with and headed back to look for the baby. He sent his pet pit bull in first to check things out, then went in through the back door. "As I preceded into the kitchen, I saw a puddle of blood, a big puddle of blood," he said. He searched everywhere but found no baby. When he told Gurrolla, that's when she first started to cry. Police said the baby's father was at the home later Tuesday night, and Sharon Kimble, who lives with Peterson, said the toddler's father came later to pick her up. Police spokesman Don Aaron said investigators were interviewing Gurrolla and her family again about the abduction. A sketch artist is working to come up with a drawing of the kidnapper's face. "We don't have any indication at this point that this is anything but a stranger child abduction," Mumford said. "We're not ruling out anything, but we have no reason to believe that the family is not being completely truthful." Mumford said police are retracing the mother's activities before the attack, such as a visit to a local Walmart. Hoping to find a witness, police released a photo of a car that was parked near Gurrolla's at the Walmart and later followed her down the road. Aaron asked the public for tips on the case and said it was a top priority for police in the area.