PARIS (REUTERS, AFP) - The French policeman who was shot three times after voluntarily taking the place of a hostage during a supermarket siege in south-western France on Friday has died, France announced on Saturday (March 24).

Arnaud Beltrame, who once served in Iraq, had been raced to hospital fighting for his life after the siege in which he took the place of a female hostage at the Super U store in the town of Trebes, near the Pyrenees mountains.

"He fell as a hero, giving up his life to halt the murderous outfit of a jihadist terrorist," President Emmanuel Macron said in a statement shortly before dawn on Saturday.

Interior Minister Gerard Collomb wrote on his Twitter account: "Lieutenant-Colonel Arnaud Beltrame has passed away. He died for his country. France will never forget his heroism."

Beltrame was part of a team of gendarmes who were among the first to arrive at the supermarket scene; most of the people in the supermarket escaped after hiding in a cold storage room and then fleeing through an emergency exit.

He offered to trade places with a hostage the attacker was still holding, whereafter he took her place and left his mobile phone on a table, line open.

When shots rang out, elite police stormed the building to kill the assailant. Police sources said Beltrame was shot three times. The 44-year-old's death takes the number killed to four.

The Islamic State in Iraq and Syria (ISIS) group claimed the attack was in response to its call to target Western enemies - as is customary when the assailant has pledged allegiance to the extremists. Macron has said security services are checking that claim.

Friday's attacker was identified by authorities as Redouane Lakdim, a 25-year-old Moroccan-born French national from the city of Carcassonne, not far from Trebes, a tranquil town of about 5,000 people where he struck on Friday afternoon.

Lakdim was known to authorities for drug-dealing and other petty crimes, but had also been under surveillance by security services in 2016-2017 for links to the radical Salafist movement, Paris prosecutor Francois Molins said on Friday.

The attacker, whose rampage began when he shot at a group of police joggers and also shot the occupants of a car he stole, killed three people and injured 16 others on Friday, according to a government readout.

Police arrested a second person overnight believed to be linked to the attack, a judicial source said on Saturday. Another source said the man, a minor born in 2000, was a friend of Lakdim, who was initially believed to have acted alone. Police arrested a woman connected to the attacker on Friday, a French prosecutor said.

The shootings come as France remains on high alert following a string of deadly attacks that have killed more than 240 people since 2015.

Security sources said Lakdim was born in Taza in northern Morocco and held French nationality. His partner, who lived with him in Carcassonne, has been detained, Molins said. Lakdim started his rampage in Carcassonne at around 10:30 am (0930 GMT), hijacking a car and shooting the two people inside, Molins said.

The passenger was killed, and the driver remains in a critical condition. Lakdim then shot and wounded a police officer who was out jogging with colleagues before driving to nearby Trebes where he burst into the Super U supermarket.

"The attacker entered the store shouting "Allahu Akbar" (God is greatest) and saying he was a soldier of the Islamic State, ready to die for Syria," Molins said.

He further demanded "the release of his brothers" from prison before shooting a supermarket customer and an employee dead. "I was five metres away from him," the store's security guard said, speaking on condition of anonymity. "He shot at me twice."

Luckily for the security guard, "he shot badly."

About 50 people were in the supermarket at the time, and though some people managed to escape, several remained inside.

Lt-Col Beltrame, who was married without children, offered to take the place of a woman Lakdim was using as a human shield while his colleagues negotiated with the gunman, Collomb said.

The officer "left his telephone on the table" to allow police who had surrounded the building to listen in, Collomb said. When special forces heard shots they stormed the store, killing the gunman and recovering Beltrame, who had been seriously wounded.

French media reports said on Saturday (March 24) that Beltrame had participated in the local police force's simulation of a supermarket terror attack only months ago, in December 2017. Such exercises are regularly held by the security forces since an ISIS-linked gunman stormed a Jewish supermarket just outside Paris in January 2015, killing four people.

Beltrame, who would have turned 45 in April, was a qualified parachutist who served in Iraq in 2005. He also worked as part of the elite Republican Guard that protects the presidential Elysee Place offices and residence in Paris, Macron said.

Trebes, a sleepy town of 5,000 people along the Canal du Midi, was on lockdown throughout Friday as helicopters swirled overhead and heavily armed and masked police carried out a massive operation in Lakdim's neighbourhood.

The fact that Lakdim had been monitored as a potential extremist will raise difficult questions for Macron's government as to how he slipped through the net. "We had monitored him and did not think he had been radicalised," Interior Minister Collomb said after flying to the scene.

"He was already under surveillance when he suddenly decided to act."

In Paris, the Eiffel Tower dimmed its lights at midnight in a mark of respect for the victims and a minute's silence was held at the Stade de France before a football match between France and Colombia.

Friday's violence took place in a part of France still scarred by a killing spree in 2012 in the city of Toulouse and nearby Montauban where another jihadist, Mohamed Merah, shot dead seven people including three Jewish schoolchildren.

That assault marked the first of several big Islamist attacks in France since 2015, including the massacre at the satirical newspaper Charlie Hebdo, the November 2015 attacks that killed 130 in Paris, and a summer 2016 truck attack during Bastille Day festivities in Nice.

The most recent assault came in October when a Tunisian man stabbed to death two women at Marseille's railway station, shouting "Allahu Akbar". A state of emergency put in place just after the 2015 Paris attacks was lifted last October when Macron's centrist government passed a new law boosting the powers of security forces.