TREBES, France－The French police officer who swapped places with a female supermarket employee being held hostage had already received a lifetime of accolades by the time he walked unarmed into the store under attack by an extremist gunman.

Known for his courage and sang-froid, Lieutenant Colonel Arnaud Beltrame was acclaimed by neighbors, colleagues and French authorities as a hero on Saturday after his death from wounds the day before. President Emmanuel Macron announced plans for a national ceremony to formally honor him.

After agreeing to the hostage swap, Beltrame surrendered his weapon but kept his cellphone on, allowing authorities outside the Super U market in the southern French town of Trebes to hear what was happening inside.

Thanks to Beltrame's quick thinking, special police units heard gunshots inside the store on Friday and stormed the building immediately, killing the attacker.

"Beyond his job, he gave his life for someone else, for a stranger," his brother, Cedric, told RTL radio in France. "He was well aware he had almost no chance. He was very aware of what he was doing ... if we don't describe him as a hero, I don't know what you need to do to be a hero."

"Arnaud Beltrame died in the service of the nation to which he had already given so much," Macron said. "In giving his life to end the deadly plan of a jihadi terrorist, he fell as a hero."

The date of the ceremony for Beltrame wasn't immediately set.

The hostage whose life he saved, an employee named Julie, was in a "catastrophic state," her manager said.

Beltrame's entire career seemed to lead inexorably to the moment when he responded to the attack on Friday in Trebes, a 15-minute drive from the gendarme unit he had led since last August.

He joined France's elite police special forces in 2003 and served in Iraq in 2005. A former member of the presidential guard, he earned one of France's highest honors, the Order of Merit, in 2012.

In December, Beltrame organized a counterterrorism training session for just such a hostage situation down to the location in a supermarket. At the time, he armed his officers with paintball guns, according to the Depeche du Midi newspaper.

"We want to be as close to real conditions as possible," he said then.

In addition to the four people killed by the gunman Friday, 15 others were injured.

Investigators searched the home of the attacker, Moroccan-born Redouane Lakdim, 25, and found what a judicial official said were notes "that alluded to the Islamic State and appeared like a last testament." They also found a computer and a phone.

Inside the market itself, investigators found three homemade explosive devices, a handgun and a hunting knife, the official said. He wasn't authorized to speak publicly amid the investigation.

The weapons suggested an intent to do further damage.

AP