The French police officer who swapped himself for 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 in life, Lieutenant Colonel Arnaud Beltrame was honoured as a national hero on Saturday after his death from wounds the day before.

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

Thanks to his 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,” President Emmanuel Macron said.

“In giving his life to end the deadly plan of a jihadi terrorist, he fell as a hero.”

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

Mr Beltrame’s entire career seemed to lead inexorably to the moment when he responded to the attack 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 honours, the Order of Merit, in 2012.

In December, Mr Beltrame organised a counter-terrorism 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 on 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.

A woman places flowers at the main gate of the Police headquarter in Carcassonne (Emilio Morenatti/AP)
A woman places flowers at the main gate of the Police headquarter in Carcassonne (Emilio Morenatti/AP)

Inside the market itself, investigators found three homemade explosive devices, a handgun and a hunting knife, the official said.

The weapons suggested an intent to do further damage.

Mr Macron called a special Defence Council meeting with key ministers on Saturday to decide the country’s next steps in combating terror.

Across the Atlantic, US President Donald Trump tweeted “We are with you @EmmanuelMacron!” and condemned “the violent actions of the attacker and anyone who would provide him support”.

French police and soldiers have been a prime target of attacks by extremists, with 10 killed in recent years, including Mr Beltrame. Dozens of others have been wounded.

Mr Beltrame’s mother told RTL radio that, for her son, “to defend the homeland” was “his reason to live”.

“He would have said to me, ‘I’m doing my job, Mom, nothing more’,” she said.

Flowers piled up in front of the Gendarmerie headquarters in the French medieval city of Carcassonne to pay tribute to Mr Beltrame. Flags at all gendarmeries were flying at half-staff.

Mr Macron said investigators will focus on finding out how the gunman got his weapon and how he became radicalised.

Two people have been detained in the case, one woman close to Lakdim and a 17-year-old male friend.

Lakdim was known to police for petty crime and drug dealing.

But since 2014, he was also on the Fiche S list, a government register of people suspected of being radicalised but who have yet to perform acts of terror.

Despite this, Paris prosecutor Francois Molins said there was “no warning sign” that Lakdim would carry out an attack.

The four-hour drama began at 10.13am on Friday when Lakdim hijacked a car near Carcassonne, killing the passenger and wounding the driver, the prosecutor said.

Lakdim then fired six shots at police officers who had just finished jogging, hitting one in the shoulder.

FRANCE Shooting
(PA Graphics)

Shouting “Allahu akbar!” — Arabic for “God is great” and declaring he was a “soldier of the Islamic State,” he entered the Super U supermarket in Trebes, 60 miles (100 kilometres) south-east of Toulouse, where about 50 people were inside, Mr Molins said.

He killed two people in the market and took an unknown number of hostages.

The supermarket’s manager, who would identify herself only as Samia, was in her office when she heard the shots.

“Call the gendarmes,” she told her employees. “There’s a terrorist in the store.”

She said she helped evacuate as many people as possible. Other people sought safety in the store’s meat locker.

During the standoff, Lakdim requested the release of Salah Abdeslam, the sole surviving assailant of the November 13 2015 attacks in Paris that left 130 people dead.

The interior minister suggested, however, that Abdeslam’s release was not a key motive.

The IS-linked Aamaq news agency said the attacker was responding to its call to target countries in the US-led coalition carrying out airstrikes against IS militants in Syria and Iraq.

Samia was overcome by emotion when asked about the attack.

“I’m utterly devastated. This is really a tragedy. I feel deeply for the victims,” she said, adding that Mr Beltrame “is a hero. He saved our colleague – our Julie.”

The mayor of Trebes, Eric Menassi, was equally emotional.

“They all looked death in the eye,” he said. “There will be a before and an after. I think nothing will ever be the same.”