The gunman charged in the deadly shooting at Los Angeles International Airport lay bloodied and handcuffed on the floor of Terminal 3 after being gunned down by police, but he replied to critical questions that helped authorities lock down the scene. Paul Ciancia, 23, was hauled away moments later on a stretcher and later heavily sedated for medical reasons, but not before he told investigators he had acted alone when he opened fire in the terminal, a law enforcement official who has been briefed on the investigation told The Associated Press on Sunday. Ciancia, an unemployed motorcycle mechanic who recently moved to Los Angeles from the small, blue-collar town of Pennsville, N.J., also told police a friend had dropped him at LAX on Friday just moments before he shot a Transportation Security Administration officer at point-blank range and wounded three other people, including two more TSA workers. Officials do not believe that the friend knew of the shooter's plans. Ciancia arrived at the airport in a black Hyundai and was not a ticketed passenger. Ciancia was under 24-hour armed guard at the hospital Sunday after being shot four times, the official said. He was sedated for medical reasons, the official said, adding that one gunshot to the mouth blew a molar out of his jaw. Ciancia is facing charges of murder of a federal officer and committing violence at an international airport. It wasn't immediately clear when he would make a first court appearance given his medical condition. In court documents and interviews, authorities spelled out a chilling chain of events, saying Ciancia walked into the airport, pulled a .223-caliber assault rifle from his duffel bag and fired repeatedly at 39-year-old TSA officer Gerardo I. Hernandez. He turned back to see Hernandez move and returned to finish him off, according to surveillance video reviewed by investigators. He then fired on two other uniformed TSA employees and an airline passenger, who all were wounded, as he moved methodically through the security checkpoint before airport police shot him as panicked travelers hid in stores and restaurants. It wasn't clear why Ciancia targeted TSA officers, but what he left behind indicated he was willing to kill any of them that crossed his path, authorities revealed. The shooter's duffel bag contained a handwritten letter signed by Ciancia stating he'd "made the conscious decision to try to kill" multiple TSA employees and that he wanted to "instill fear in their traitorous minds," FBI Agent in Charge David L. Bowdich said. When searched, the suspect had five 30-round magazines, and his bag contained hundreds more rounds in boxes. U.S. Rep. Michael McCaul, R-Texas, chairman of the House Homeland Security Committee, said on CNN's State of the Union on Sunday that Ciancia's actions show how difficult it is to protect travelers at a massive airport such as LAX.