Spencer Stone, the U.S. Airman 1st class, who was one of the three Americans to thwart an August terror attack on a train in France, was recovering at a hospital Thursday after being stabbed thrice in Sacramento, California. Police said the attack stemmed from an alcohol-related scuffle, the Associated Press (AP) reported.

Stone, a 23-year-old resident of Carmichael, California, was taken to UC Davis Medical Center and was in stable condition, according to a statement by the U.S. Air Force. He reportedly underwent surgery and was placed in the intensive care unit.

UC Davis Chief Medical Officer Douglas Kirk said Stone was conscious when he reached the hospital and had “significant injuries” on his torso. "I suspect given his history of recent events, he is quite a fighter," Kirk said, according to AP.

Ken Bernard, Sacramento’s deputy police chief, said the attack was not associated with terrorism. "We know it's not related to what occurred in France months ago," Bernard reportedly said.

According to Bernard, the stabbing was "related to a nightclub incident" involving Stone's group and other people, CBS News reported. The officer said there was no evidence Stone's attackers knew who he was and it was unclear whether Stone was drinking. However, others in his group were drinking, Bernard reportedly said.

CBS News, citing a law enforcement official, reported that after Stone's group left the bar, he and a suspect engaged in an argument, leading to the attack. Stone was unarmed at the time of the incident, the official said.

Sacramento Police Department have launched an investigation into the attack and released CCTV footage of what they believe is the suspects' vehicle fleeing the scene. “Two suspects, involved in the altercation, are seen entering the car (believed to be a 2009-2012 Toyota Camry, dark in color) before it drives out of the area,” the department said, in a Facebook statement.

In August, Stone and his two friends, Anthony Sadler and Alek Skarlatos, a member of the Oregon Army National Guard, along with three others, subdued a man armed with an AK-47 assault rifle, a pistol and a box-cutter on a high-speed train bound for Paris. They were praised for their actions and were hailed as heroes in France and the U.S.

Stone sustained a slash on the neck and had his thumb almost sliced off by the suspected terrorist, identified as Moroccan national Ayoub el-Khazzani, 26, who was on the radar of French, Spanish and Belgian security officials.