The former Navy SEAL who killed Usama bin Laden heaped praise on the three Americans who acted heroically Friday to stop a terrorist gunman on a train in France.

When the terrorist pulled out an AK-47, Sacramento State University senior Anthony Sadler, Air Force serviceman Spencer Stone and National Guardsman Alek Skarlatos jumped into action and eventually subdued him, saving countless lives.

The men spoke about the incident yesterday, as President Francois Hollande awarded them France's Legion of Honor for their heroism. 

Stone, who suffered several wounds in the struggle, said they began punching the suspect, and he eventually was able to choke him unconscious.

"He seemed like he was ready to fight to the end. So were we," Stone said.

O'Neill said he was fortunate while in the military that any time someone pointed a gun at him, he was also armed. But he said the three men were on holiday, napping on a train and unarmed when the gunman emerged.

He said the men's heroism reminds him of what the passengers did on Flight 93 on Sept. 11, 2001.

"Let's roll, like the Todd Beamer thing on Flight 93. Get up and fight. Actively participate in saving your own life and the lives of others," he said.

O'Neill noted that the gunman had eight magazines of 30 rounds and could have murdered a lot of passengers.

O'Neill said he was struck by the "humility" of the men at their press conference, adding that he's proud of the "guts" and courage the men displayed.

Watch the discussion above.