LOS ANGELES • One of three Americans who helped thwart a terror attack on a Paris-bound train was stabbed in his home state of California - apparently after coming to a woman's rescue.

Airman Spencer Stone, 23, was stabbed in Sacramento after he got into a fight with a group of men as he was leaving a bar with friends at about 1am on Thursday, Mr Ken Bernard, the city's deputy chief of police, told reporters.

Mr Bernard said officers found Mr Stone with multiple stab wounds to his upper body. He was listed in serious condition after two hours of surgery.

"He is currently being treated for what appears to be non-life threatening but very significant injuries," Mr Bernard said, adding that two male Asian suspects were being sought in connection with the attack.

A source close to the investigation told news agency Agence Francre-Presse that Mr Stone was apparently trying to defend a woman being harassed by a group of men outside the bar when an argument escalated. It was unclear if the woman was with Mr Stone.

"A woman was being harassed and he got involved," said the source, who spoke on condition of anonymity. The source said several of those in Mr Stone's group - three women and another man - were drunk, but it was unclear if Mr Stone himself was inebriated.

Video footage of the incident caught by a nearby surveillance camera and released by US media shows Mr Stone fighting off a group of men, who scatter when what appears to be a police car arrives.

A red stain can be seen spreading on Mr Stone's white shirt.

Another surveillance video released by police shows the two suspects involved in the altercation running and getting into a car that drives off quickly.

Mr Bernard said the assault was in no way related to a terrorist act or to the train attack that Mr Stone and two of his friends helped foil while vacationing in France.

Just weeks ago, the town of Sacramento staged a "Heroes Parade" in honour of the trio. Mr Stone suffered deep slash wounds as he helped to overpower a heavily armed gunman, 25-year-old Moroccan Ayoub El Khazzani, on Aug 21.

Armed with a pistol, an assault rifle and 270 rounds of ammunition, Khazzani is accused of seeking to massacre passengers on the train.

Mr Stone was awarded the Legion of Honour, France's highest decoration, along with Army National Guard Specialist Alek Skarlatos and Mr Anthony Sadler, a civilian.

AGENCE-FRANCE PRESSE