Spencer Stone, one of the men who foiled a terror attack on a Paris-bound train in August, was seriously injured after being stabbed several times near a bar in downtown Sacramento early Thursday morning, PEOPLE confirms.

Stone is in serious condition at UC-Davis Medical Center, the hospital said in a statement. Sacramento is near Travis Air Force Base, where Stone is stationed.

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In a statement, the Sacramento Police Department said they received a call from a passerby saying the stabbing had occurred in the area of 21st Street and K Street. Deputy Chief Ken Bernard of the Sacramento Police Department said at a press conference that Stone sustained “non-life-threatening but very significant injuries.” He said that Stone was stabbed after a physical altercation near a bar, and described the suspects as two Asian males wearing white T-shirts and blue jeans, who then fled the scene, and were seen leaving in a 2009 to 2012 Toyota Camry.

Prior to the stabbing, Bernard said “there were conversations” between the group of people Stone was with and suspects. “And it continued down the block [from the bar] to where the stabbing occurred.”

Prior to the press conference, Sacramento police tweeted: The assault incident is not related to a terrorist act. Assault occurred near a bar, alcohol is believed to be a factor.”

Bernard said that members of Stone’s party were drinking, but he could not comment on whether Stone was drinking or not, adding that police have no reason to believe Stone is in any kind of trouble. He said that he would not get into the specifics of the confrontation as the incident is currently under investigation.

The Sacramento Bee shows what it says is surveillance video taken from a nearby store of the fight, showing a man in a white shirt who appears to be Stone fighting with at least two other men. Spencer Stone’s father, Brian Stone, tells PEOPLE he still wasn’t exactly sure of the details of what happened: “He’s out of surgery and doing well. He’s been upgraded so no longer critical and it looks like he’s going to be okay. All I can say is that this world is not short of idiots.”

Brian Stone tells PEOPLE that Stone was admitted in critical condition and was upgraded to serious after surgery.

According to The Air Force Times, cops initially thought Stone would not survive and began treating the incident as a homicide investigation.

In a statement, UC-Davis Medical Center said, “The family of Airman Spencer Stone appreciates the outpouring of love and support.”

Stone, 23, previously sustained a serious injury while trying to subdue terror suspect Ayoub El-Khazzani on the Paris-bound train earlier this summer. El-Khazaani, who allegedly opened fire on the train, allegedly stabbed Stone with a box cutter. Stone needed surgery to reattach part of his hand.

Stone’s fellow hero and childhood friend, Alex Skarlatos, tweeted out his well-wishes:

Rich Wisdom, 48, a friend of Stone’s who worked with him at Raly’s grocery store, tells PEOPLE, “We had just talked on Facebook on Saturday and he said he was going to swing by the store to say hi while he was in town, but then this awful thing happened. I’m just praying that all of his injuries heal quickly. He’s a real hero.”

• With reporting by SUSAN YOUNG