PLANT CITY — After two teenagers were pulled from a burning house early Tuesday, they told police officers this: Their mom was still inside. And she was being attacked.According to Plant City police, Officer James Burchett walked out the front door and around to the back. Through a bedroom window, he spotted a man stabbing a woman. He shouted for the man to stop. When he didn't, Burchett went for his gun. With a single shot, the assailant fell dead.Police identified him as 31-year-old Trung Thanh Do of Plant City.The woman, Maria De Los Angeles Romano, 43, of Plant City survived the assault with nonlife-threatening injuries to her upper torso. Police said she was taken to a hospital, where she was expected to recover.Police released no motive for the attack. State records show that Do had no criminal past in Florida — only a traffic ticket in Hillsborough County from August.Authorities got a call about a house fire at 107 S Maryland Ave. just before 4 a.m. Tuesday. The caller told dispatchers four people were inside. Officers arrived at the home, which Romano bought about a year ago, and found a burning carport as well as a 13-year-old girl and an 18-year-old woman who said their mother was being assaulted in a locked bedroom, according to Plant City police Chief Ed Duncan.The teens were uninjured. They remained in police custody Tuesday until they could be reunited with their mother and other family members who could care for them.Burchett, a five-year employee of the Plant City Police Department, was placed on paid administrative leave while the Florida Department of Law Enforcement investigates, which is standard in police shootings. Burchett spent seven years with the Pittsylvania County Sheriff's Office in Chatham, Va., and one year with the Polk County Sheriff's Office before arriving in Plant City.Dozens of law enforcement officials remained on the scene into the afternoon. The house, badly charred on one side and still releasing light smoke, stands directly across the street from Marshall Middle School, which was closed Tuesday in observance of Veterans Day. Official vehicles lined the school's semi-circle driveway and crime scene tape cordoned off the block.The state fire marshal determined the cause of the fire to be arson, Duncan said. Authorities believed Do started it, but that remained under investigation.Duncan said Plant City detectives would continue to investigate the stabbing and the arson in conjunction with the fire marshal.Times news researcher John Martin and staff writer Keeley Sheehan contributed to this report. Contact Josh Solomon at (813) 226-3446 or [email protected] Follow @josh_solomon15.