SAN FRANCISCO (KGO) -- Police in San Francisco are investigating after an attacker attempted to abduct a baby Sunday evening.Police say the attacker tried to grab a woman's newborn baby on Natoma Street in the Mission District.There was a struggle with the baby caught in the middle, but the mother eventually got her baby back.The attacker and three others ran away.Police have arrested them-and they have been positively identified by the mother and witnesses. The baby is being checked out at the hospital. Police were talking to witnesses and gathering evidence at the scene.