New footage shows two suspects getting into a car and fleeing after Spencer Stone was stabbed multiple times in the chest early on Thursday.
Stone, who was hailed as a hero for thwarting a terrorist attack on a Paris-bound train this summer, is in stable condition in hospital.
The 23-year-old was stabbed during a night out in his hometown of Sacramento, California. He was leaving a nightclub with friends at about 1 a.m. when there was an altercation with another group, police said.
Stone was reportedly coming to the aid of another friend when he was stabbed.
New video released by the Sacramento Police Department shows two of the suspects jumping into a dark Toyota Camry before driving away. Deputy Police Chief Ken Bernard said authorities are looking for two Asian men who were wearing blue jeans and white T-shirts at the time.
In other surveillance footage captured from a nearby liquor store, a fight can be seen breaking out in the street. Officers say Stone appears to be the man in the long-sleeve white shirt, who is seen throwing and taking punches before backing away.
Dark patches, which appear to be blood, can also be seen on his white shirt.
Stone is out of surgery and listed in serious but stable condition. His care team anticipates he will make a full recovery, said Douglas Kirk, Chief Medical Officer of UC Davis Medical Center.
Police initially did not think he was going to survive and began treating the incident as a homicide investigation, according to reports.
Stone was one of three Americans who took down Ayooub El-Khazaani after the Morocco-born terror suspect opened fire on a Paris-bound train in August. He was stabbed with a box cutter during the struggle with El-Khazaani and underwent surgery to reattach part of his hand.
He, along with friends Alek Skarlatos and Anthony Sadler, received France's highest award, the Legion d'Honneur, for their actions.
President Barack Obama commended the three men for their bravery, saying at the time that "they represent the very best of American character."
Skarlatos tweeted about the Thursday incident, writing:
Spencer is one tough guy. And only he could have done something like that and lived, yet again— alek skarlatos (@alekskarlatos) October 8, 2015
Watch Below: President Obama Meets American Train Heroes: They Are The Best of America