A seven-year-old girl was stabbed three times in the shoulder by a 10-year-old boy on the playground of her elementary school in an ultra-wealthy Bay Area neighborhood . Investigators say its unclear if the pair even know each other. The kid knifed the girl, then took off into the upscale Mountain View area with police in hot pursuit. They eventually caught him with the help of home surveillance footage and a K-9 unit. The boy allegedly used a kitchen knife that was recovered on the Bubb