US man who helped stop French train attack stabbed

US Air Force official Spencer Stone, who helped stop a gunman on a French train in August, was stabbed in California, air force officials said.

Airman First Class Stone was stabbed multiple times and was in critical condition on Thursday near some popular bars in downtown Sacramento, Xinhua quoted Sacramento police officer Traci Trapani as saying.

Stone had an argument with an "unknown suspect". The assailant pulled out a knife and stabbed him multiple times, Trapani said.

Stone is in stable condition now, said Lt. Col. Christopher Karns, an air force spokesman.

Stone and his friends Anthony Sadler, 23, and Army National Guard's Alek Skarlatos, 22, are credited with taking down Ayoub El Khazzani, a Moroccan man, after he opened fire on a train travelling from Amsterdam to Paris on August 21.

Thursday's incident remained under investigation by police.