The fatal shot ended a three-hour standoff with police near 44th and 170th E. Ave in Tulsa.
Police said Reyes, 44, broke into his estranged wife's home late Monday night. The woman was able to escape the house with three children and her boyfriend. Reyes was the father of the three children who fled the house.
Reyes made several threatening gestures from the home's balcony pointing the handgun at the girl and officers. The two-year-old hostage was not related to Reyes.
According to Tulsa Police Department, Lawless has been with the department 18 years. He is on paid administrative leave.